Method for receiving downlink signal by terminal in wireless communication system, and device therefor

ABSTRACT

Various embodiments provide a method for receiving a physical downlink shared channel (PDSCH) from a non-terrestrial network (NTN) by a terminal in a wireless communication, and a device therefor. Disclosed are a method and a device therefor, the method comprising the steps of: receiving semi-persistent scheduling configuration information; receiving first downlink control information (DCI) for activating an SPS configuration related to the SPS configuration information; receiving the PDSCH on the basis of the SPS configuration; and determining, on the basis of the SPS configuration, whether to perform hybrid automatic repeat and request (HARQ) feedback of an HARQ process for the PDSCH.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2021/008470, filed on Jul. 5, 2021, which claims the benefit of earlier filing date and right of priority to Korean Application Nos. 10-2020-0082097, filed on Jul. 3, 2020, 10-2020-0085628, filed on Jul. 10, 2020, and 10-2020-0095499, filed on Jul. 30, 2020, the contents of which are all incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present disclosure relates to a method for a user equipment (UE) to determine a hybrid automatic repeat and request (HARQ) procedure is performed by receiving a physical downlink shared channel (PDSCH) from a non-terrestrial network (NTN) in a wireless communication system and an apparatus therefor.

BACKGROUND

Wireless communication systems have been widely deployed to provide various types of communication services such as voice or data. In general, a wireless communication system is a multiple access system that supports communication of multiple users by sharing available system resources (a bandwidth, transmission power, etc.). Examples of multiple access systems include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, a single carrier frequency division multiple access (SC-FDMA) system, and a multi carrier frequency division multiple access (MC-FDMA) system.

As more and more communication devices require larger communication capacities in transmitting and receiving signals, there is a need for mobile broadband communication improved from the legacy radio access technology. Accordingly, communication systems considering services/UEs sensitive to reliability and latency are under discussion. A next-generation radio access technology in consideration of enhanced mobile broadband communication, massive Machine Type Communication (MTC), and Ultra-Reliable and Low Latency Communication (URLLC) may be referred to as new radio access technology (RAT) or new radio (NR).

SUMMARY

An object of the present disclosure to be solved is to provide a method and an apparatus for indicating or configuring both a semi-persistent scheduling (SPS) configuration through SPS configuration information and HARQ feedback-enabled/disabled for the SPS configuration.

It will be appreciated by those of ordinary skill in the art to which the embodiment(s) pertain that the objects that could be achieved with the embodiment(s) are not limited to what has been particularly described hereinabove and the above and other objects will be more clearly understood from the following detailed description.

According to an aspect of the present disclosure, provided herein is a method of receiving a physical downlink shared channel (PDSCH) by a user equipment (UE) from a non-terrestrial network (NTN) in a wireless communication system, including receiving semi-persistent scheduling (SPS) configuration information, receiving first downlink control information (DCI) that activates an SPS configuration related to the SPS configuration information, receiving the PDSCH based on the SPS configuration, and determining whether to perform hybrid automatic repeat and request (HARQ) feedback of a HARQ process for the PDSCH based on the SPS configuration.

The UE may transmit acknowledgement/negative acknowledgement (ACK/NACK) for the PDSCH based on the HARQ feedback of at least one HARQ process for the SPS configuration being enabled based on the SPS configuration information.

The SPS configuration information may include a first SPS configuration in which HARQ feedback of at least one HARQ process is enabled and a second SPS configuration in which the HARQ feedback of the at least one HARQ process is disabled.

The SPS configuration information may further include an SPS index indicating any one of the first SPS configuration and the second SPS configuration as the SPS configuration.

The UE may transmit acknowledgement/negative acknowledgement (ACK/NACK) for the PDSCH based on the first SPS configuration being indicated as the SPS configuration by the SPS index.

The method may further include receiving second DCI that changes HARQ feedback-enabled or HARQ feedback-disabled for at least one HARQ process configured for the SPS configuration.

Activation or deactivation of the SPS configuration may be determined based on a combination of bits included in at least two fields among a redundancy version (RV) field, a HARQ process number, a modulation and coding scheme (MCS) field, and a frequency resource assignment field, included in the first DCI.

The NTN may be related to at least one of a geostationary orbit (GEO) satellite, a medium-earth orbit (MEO) satellite, a high elliptical orbit (HEO) satellite, a high altitude platform station (HAPS), or a low earth orbit (LEO) satellite.

In another aspect of the present disclosure, provided herein is a method of transmitting a physical downlink shared channel (PDSCH) by a non-terrestrial network (NTN) in a wireless communication system, including transmitting semi-persistent scheduling (SPS) configuration information, transmitting first downlink control information (DCI) that activates an SPS configuration related to the SPS configuration information, transmitting the PDSCH based on the SPS configuration, and determining whether to receive feedback information for a hybrid automatic repeat and request (HARQ) for the PDSCH based on the SPS configuration.

The SPS configuration information may include a first SPS configuration in which HARQ feedback of at least one HARQ process is enabled and a second SPS configuration in which the HARQ feedback of the at least one HARQ process is disabled.

The NTN may determine whether HARQ feedback of at least one HARQ process for the SPS configuration is enabled or disabled based on channel information for the PDSCH and quality of service (QoS) of a transport block related to the PDSCH.

In another aspect of the present disclosure, provided herein is a user equipment (UE) for receiving a physical downlink shared channel (PDSCH) from a non-terrestrial network (NTN) in a wireless communication system, including a radio frequency (RF) transceiver and a processor connected to the RF transceiver. The processor may receive semi-persistent scheduling (SPS) configuration information, receive first downlink control information (DCI) that activates an SPS configuration related to the SPS configuration information, and receive the PDSCH based on the SPS configuration, by controlling the RF transceiver, and determine whether to perform hybrid automatic repeat and request (HARQ) feedback of a HARQ process for the PDSCH based on the SPS configuration.

In another aspect of the present disclosure, provided herein is a non-terrestrial network (NTN) for transmitting a physical downlink shared channel (PDSCH) in a wireless communication system, including a radio frequency (RF) transceiver and a processor connected to the RF transceiver. The processor may transmit semi-persistent scheduling (SPS) configuration information, transmit first downlink control information (DCI) that activates an SPS configuration related to the SPS configuration information, and transmit the PDSCH based on the SPS configuration, by controlling the RF transceiver, and determine whether to receive feedback information for a hybrid automatic repeat and request (HARQ) for the PDSCH based on the SPS configuration.

In another aspect of the present disclosure, provided herein is a chipset for receiving a physical downlink shared channel (PDSCH) from a non-terrestrial network (NTN) in a wireless communication system, including at least one processor and at least one memory operably connected to the at least one processor and causing, when executed, the at least one processor to perform operations. The operations may include receiving semi-persistent scheduling (SPS) configuration information, receiving first downlink control information (DCI) that activates an SPS configuration related to the SPS configuration information, receiving the PDSCH based on the SPS configuration, and determining whether to perform hybrid automatic repeat and request (HARQ) feedback of a HARQ process for the PDSCH based on the SPS configuration.

In another aspect of the present disclosure, provided herein is a computer readable storage medium including at least one computer program that performs operations of receiving a physical downlink shared channel (PDSCH) from a non-terrestrial network (NTN) in a wireless communication system. The at least one computer program may be configured to cause at least one processor to perform the operations of receiving the PDSCH and be stored in the computer readable storage medium. The operations may include receiving semi-persistent scheduling (SPS) configuration information, receiving first downlink control information (DCI) that activates an SPS configuration related to the SPS configuration information, receiving the PDSCH based on the SPS configuration, and determining whether to perform hybrid automatic repeat and request (HARQ) feedback of a HARQ process for the PDSCH based on the SPS configuration.

According to various embodiments, both an SPS configuration and HARQ feedback-enabled/disabled for the SPS configuration may be indicated to or configured for the UE through SPS configuration information.

Effects to be achieved by embodiment(s) are not limited to what has been particularly described hereinabove and other effects not mentioned herein will be more clearly understood by persons skilled in the art to which embodiment(s) pertain from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the present disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the principle of the present disclosure.

FIG. 1 illustrates the structure of an LTE system.

FIG. 2 illustrates the structure of an NR system.

FIG. 3 illustrates the structure of an NR radio frame.

FIG. 4 illustrates the slot structure of an NR frame.

FIG. 5 illustrates a procedure in which a base station (BS) transmits a downlink signal to a UE.

FIG. 6 illustrates a procedure in which a UE transmits an uplink signal to a BS.

FIG. 7 illustrates an example of time domain resource allocation for a PDSCH by a PDCCH and an example of time domain resource allocation for a PUSCH by a PDCCH.

FIG. 8 is a diagram illustrating a HARQ-ACK operation in relation to operation of a UE for reporting control information.

FIG. 9 illustrates a non-terrestrial network (NTN).

FIG. 10 illustrates an overview and a scenario of an NTN.

FIG. 11 illustrates TA components of the NTN.

FIG. 12 is a flowchart illustrating a method for a UE to perform a UL transmission operation based on embodiments.

FIG. 13 is a flowchart illustrating a method for a UE to perform a DL reception operation based on embodiments.

FIG. 14 is a flowchart illustrating a method for a BS to perform a UL reception operation based on embodiments.

FIG. 15 is a flowchart illustrating a method for a BS to perform a DL transmission operation based on embodiments.

FIGS. 16 and 17 are flowcharts illustrating methods of performing signaling between a BS and a UE based on embodiments.

FIG. 18 is a diagram illustrating a method for a UE to receive a PDSCH from an NTN.

FIG. 19 is a diagram illustrating a method for an NTN to transmit a PDSCH to a UE.

FIG. 20 illustrates a communication system applied to the present disclosure.

FIG. 21 illustrates wireless devices applicable to the present disclosure.

FIG. 22 illustrates another example of a wireless device to which the present disclosure is applied.

DETAILED DESCRIPTION

The wireless communication system is a multiple access system that supports communication with multiple users by sharing available system resources (e.g., bandwidth, transmission power, etc.). Examples of the multiple access system include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, a single carrier frequency (SC-FDMA) system, a multi carrier frequency division multiple access (MC-FDMA) system, and the like.

A sidelink refers to a communication scheme in which a direct link is established between user equipments (UEs) to directly exchange voice or data between UEs without assistance from a base station (BS). The sidelink is being considered as one way to address the burden on the BS caused by rapidly increasing data traffic.

Vehicle-to-everything (V2X) refers to a communication technology for exchanging information with other vehicles, pedestrians, and infrastructure-built objects through wired/wireless communication. V2X may be divided into four types: vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P). V2X communication may be provided through a PC5 interface and/or a Uu interface.

As more and more communication devices require larger communication capacities in transmitting and receiving signals, there is a need for mobile broadband communication improved from the legacy radio access technology. Accordingly, communication systems considering services/UEs sensitive to reliability and latency are under discussion. A next-generation radio access technology in consideration of enhanced mobile broadband communication, massive MTC, and Ultra-Reliable and Low Latency Communication (URLLC) may be referred to as new radio access technology (RAT) or new radio (NR). Even in NR, V2X communication may be supported.

Techniques described herein may be used in various wireless access systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier-frequency division multiple access (SC-FDMA), etc. CDMA may be implemented as a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented as a radio technology such as global system for mobile communications (GSM)/general packet radio service (GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented as a radio technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, evolved-UTRA (E-UTRA) etc. UTRA is a part of universal mobile telecommunications system (UMTS). 3GPP LTE is a part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA for downlink and SC-FDMA for uplink. LTE-A is an evolution of 3GPP LTE. 3GPP NR (New Radio or New Radio Access Technology) is an evolved version of 3GPP LTE/LTE-A/LTE-A pro.

5G NR is a successor technology of LTE-A, and is a new clean-slate mobile communication system with characteristics such as high performance, low latency, and high availability. 5G NR may utilize all available spectrum resources, from low frequency bands below 1 GHz to intermediate frequency bands from 1 GHz to 10 GHz and high frequency (millimeter wave) bands above 24 GHz.

For clarity of explanation, LTE-A or 5G NR is mainly described, but the technical spirit of the embodiment(s) is not limited thereto

FIG. 1 illustrates the structure of an LTE system to which the present disclosure is applicable. This may also be called an evolved UMTS terrestrial radio access network (E-UTRAN) or LTE/LTE-A system.

Referring to FIG. 1 , the E-UTRAN includes evolved Node Bs (eNBs) 20 which provide a control plane and a user plane to UEs 10. A UE 10 may be fixed or mobile, and may also be referred to as a mobile station (MS), user terminal (UT), subscriber station (SS), mobile terminal (MT), or wireless device. An eNB 20 is a fixed station communication with the UE 10 and may also be referred to as a base station (BS), a base transceiver system (BTS), or an access point.

eNBs 20 may be connected to each other via an X2 interface. An eNB 20 is connected to an evolved packet core (EPC) 39 via an S1 interface. More specifically, the eNB 20 is connected to a mobility management entity (MME) via an S1-MME interface and to a serving gateway (S-GW) via an S1-U interface.

The EPC 30 includes an MME, an S-GW, and a packet data network-gateway (P-GW). The MME has access information or capability information about UEs, which are mainly used for mobility management of the UEs. The S-GW is a gateway having the E-UTRAN as an end point, and the P-GW is a gateway having a packet data network (PDN) as an end point.

Based on the lowest three layers of the open system interconnection (OSI) reference model known in communication systems, the radio protocol stack between a UE and a network may be divided into Layer 1 (L1), Layer 2 (L2) and Layer 3 (L3). These layers are defined in pairs between a UE and an Evolved UTRAN (E-UTRAN), for data transmission via the Uu interface. The physical (PHY) layer at L1 provides an information transfer service on physical channels. The radio resource control (RRC) layer at L3 functions to control radio resources between the UE and the network. For this purpose, the RRC layer exchanges RRC messages between the UE and an eNB.

FIG. 2 illustrates the structure of a NR system to which the present disclosure is applicable.

Referring to FIG. 2 , a next generation radio access network (NG-RAN) may include a next generation Node B (gNB) and/or an eNB, which provides user-plane and control-plane protocol termination to a UE. In FIG. 2 , the NG-RAN is shown as including only gNBs, by way of example. A gNB and an eNB are connected to each other via an Xn interface. The gNB and the eNB are connected to a 5G core network (5GC) via an NG interface. More specifically, the gNB and the eNB are connected to an access and mobility management function (AMF) via an NG-C interface and to a user plane function (UPF) via an NG-U interface.

FIG. 3 illustrates the structure of a NR radio frame to which the present disclosure is applicable.

Referring to FIG. 3 , a radio frame may be used for UL transmission and DL transmission in NR. A radio frame is 10 ms in length, and may be defined by two 5-ms half-frames. An HF may include five 1-ms subframes. A subframe may be divided into one or more slots, and the number of slots in an SF may be determined according to a subcarrier spacing (SCS). Each slot may include 12 or 14 OFDM(A) symbols according to a cyclic prefix (CP).

In a normal CP (NCP) case, each slot may include 14 symbols, whereas in an extended CP (ECP) case, each slot may include 12 symbols. Herein, a symbol may be an OFDM symbol (or CP-OFDM symbol) or an SC-FDMA symbol (or DFT-s-OFDM symbol).

Table 1 below lists the number of symbols per slot N^(slot) _(symb), the number of slots per frame N^(frame,u) _(slot), and the number of slots per subframe N^(subframe,u) _(slot) according to an SCS configuration μ, in the NCP case.

TABLE 1 SCS (15*2^(u)) N^(slot) _(symb) N^(frame, u) _(slot) N^(subframe, u) _(slot) 15 KHz (u = 0) 14 10 1 30 KHz (u = 1) 14 20 2 60 KHz (u = 2) 14 40 4 120 KHz (u = 3) 14 80 8 240 KHz (u = 4) 14 160 16

Table 2 below lists the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to an SCS in the ECP case.

TABLE 2 SCS (15*2^(u)) N^(slot) _(symb) N^(frame, u) _(slot) N^(subframe, u) _(slot) 60 KHz (u = 2) 12 40 4

In the NR system, different OFDM(A) numerologies (e.g., SCSs, CP lengths, etc.) may be configured for a plurality of cells aggregated for one UE. Thus, the (absolute) duration of a time resource (e.g., SF, slot, or TTI) including the same number of symbols may differ between the aggregated cells (such a time resource is commonly referred to as a time unit (TU) for convenience of description).

In NR, multiple numerologies or SCSs to support various 5G services may be supported. For example, a wide area in conventional cellular bands may be supported when the SCS is 15 kHz, and a dense urban environment, lower latency, and a wider carrier bandwidth may be supported when the SCS is 30 kHz/60 kHz. When the SCS is 60 kHz or higher, a bandwidth wider than 24.25 GHz may be supported to overcome phase noise.

The NR frequency band may be defined as two types of frequency ranges. The two types of frequency ranges may be FR1 and FR2. The numerical values of the frequency ranges may be changed. For example, the two types of frequency ranges may be configured as shown in Table 3 below. Among the frequency ranges used in the NR system, FR1 may represent “sub 6 GHz range” and FR2 may represent “above 6 GHz range” and may be called millimeter wave (mmW).

TABLE 3 Frequency Range Corresponding Subcarrier designation frequency range Spacing (SCS) FR1  450 MHz-6000 MHz 15, 30, 60 kHz FR2 24250 MHz-52600 MHz 60, 120, 240 kHz

As mentioned above, the numerical values of the frequency ranges of the NR system may be changed. For example, FR1 may include a band of 410 MHz to 7125 MHz as shown in Table 4 below. That is, FR1 may include a frequency band of 6 GHz (or 5850 MHz, 5900 MHz, 5925 MHz, etc.) or higher. For example, the frequency band of 6 GHz (or 5850 MHz, 5900 MHz, 5925 MHz, etc.) or higher included in FR1 may include an unlicensed band. The unlicensed band may be used for various purposes, for example, for communication for vehicles (e.g., autonomous driving).

TABLE 4 Frequency Range Corresponding Subcarrier designation frequency range Spacing (SCS) FR1  410 MHz-7125 MHz 15, 30, 60 kHz FR2 24250 MHz-52600 MHz 60, 120, 240 kHz

FIG. 4 illustrates the slot structure of a NR frame to which the present disclosure is applicable.

Referring to FIG. 4 , one slot includes a plurality of symbols in the time domain. For example, one slot may include 14 symbols in a normal CP and 12 symbols in an extended CP. Alternatively, one slot may include 7 symbols in the normal CP and 6 symbols in the extended CP.

A carrier may include a plurality of subcarriers in the frequency domain. A resource block (RB) is defined as a plurality of consecutive subcarriers (e.g., 12 subcarriers) in the frequency domain. A bandwidth part (BWP) may be defined as a plurality of consecutive (P)RBs in the frequency domain, and the BWP may correspond to one numerology (e.g., SCS, CP length, etc.). The carrier may include up to N (e.g., 5) BWPs. Data communication may be conducted in an activated BWP. In a resource grid, each element may be referred to as a resource element (RE) and may be mapped to one complex symbol.

The wireless interface between UEs or the wireless interface between a UE and a network may be composed of an L1 layer, an L2 layer, and an L3 layer. In various embodiments of the present disclosure, the L1 layer may represent a physical layer. The L2 layer may represent, for example, at least one of a MAC layer, an RLC layer, a PDCP layer, and an SDAP layer. The L3 layer may represent, for example, an RRC layer.

Bandwidth Part (BWP)

In the NR system, up to 400 MHz may be supported per component carrier (CC). If a UE operating on a wideband CC always operates with the RF for the entire CCs turned on, the battery consumption of the UE may be increased. Alternatively, considering various use cases (e.g., eMBB, URLLC, Mmtc, V2X, etc.) operating within one wideband CC, different numerologies (e.g., sub-carrier spacings) may be supported for different frequency bands within a specific CC. Alternatively, the capability for the maximum bandwidth may differ among the UEs. In consideration of this, the BS may instruct the UE to operate only in a partial bandwidth, not the entire bandwidth of the wideband CC. The partial bandwidth is defined as a bandwidth part (BWP) for simplicity. Here, the BWP may be composed of resource blocks (RBs) contiguous on the frequency axis, and may correspond to one numerology (e.g., sub-carrier spacing, CP length, slot/mini-slot duration).

The BS may configure multiple BWPs in one CC configured for the UE. For example, a BWP occupying a relatively small frequency region may be configured in a PDCCH monitoring slot, and a PDSCH indicated by the PDCCH in a larger BWP may be scheduled. Alternatively, when UEs are concentrated in a specific BWP, some of the UEs may be configured in another BWP for load balancing. Alternatively, a spectrum in the middle of the entire bandwidth may be punctured and two BWPs on both sides may be configured in the same slot in consideration of frequency-domain inter-cell interference cancellation between neighbor cells. That is, the BS may configure at least one DL/UL BWP for the UE associated with the wideband CC and activate at least one DL/UL BWP among the configured DL/UL BWP(s) at a specific time (through L1 signaling, MAC CE or RRC signalling, etc.). The BS may instruct the UE to switch to another configured DL/UL BWP (through L1 signaling, MAC CE or RRC signalling, etc.). Alternatively, when a timer expires, the UE may switch to a predetermined DL/UL BWP. The activated DL/UL BWP is defined as an active DL/UL BWP. The UE may fail to receive DL/UL BWP configuration during an initial access procedure or before an RRC connection is set up. A DL/UL BWP assumed by the UE in this situation is defined as an initial active DL/UL BWP.

FIG. 5 illustrates a procedure in which a base station transmits a downlink (DL) signal to a UE

Referring to FIG. 5 , the BS schedules DL transmission in relation to, for example, frequency/time resources, a transport layer, a DL precoder, and an MCS (S1401). In particular, the BS may determine a beam for PDSCH transmission to the UE through the above-described operations.

The UE receives downlink control information (DCI) for DL scheduling (i.e., including scheduling information about the PDSCH) from the BS on the PDCCH (S1402).

DCI format 1_0 or 1_1 may be used for DL scheduling. In particular, DCI format 1_1 includes the following information: an identifier for DCI formats, a bandwidth part indicator, frequency domain resource assignment, time domain resource assignment, a PRB bundling size indicator, a rate matching indicator, a ZP CSI-RS trigger, antenna port(s), transmission configuration indication (TCI), an SRS request, and a demodulation reference signal (DMRS) sequence initialization.

In particular, according to each state indicated in the antenna port(s) field, the number of DMRS ports may be scheduled, and single-user (SU)/multi-user (MU) transmission may also be scheduled.

In addition, the TCI field is configured in 3 bits, and the QCL for the DMRS is dynamically indicated by indicating a maximum of 8 TCI states according to the value of the TCI field.

The UE receives DL data from the BS on the PDSCH (S1403).

When the UE detects a PDCCH including DCI format 1_0 or 1_1, it decodes the PDSCH according to an indication by the DCI. Here, when the UE receives a PDSCH scheduled by DCI format 1, a DMRS configuration type may be configured for the UE by a higher layer parameter ‘dmrs-Type’, and the DMRS type is used to receive the PDSCH. In addition, the maximum number of front-loaded DMRS symbols for the PDSCH may be configured for the UE by the higher layer parameter ‘maxLength’.

In the case of DMRS configuration type 1, when a single codeword is scheduled for the UE and an antenna port mapped to an index of {2, 9, 10, 11, or 30} is specified, or when two codewords are scheduled for the UE, the UE assumes that any of the remaining orthogonal antenna ports is not associated with PDSCH transmission to another UE.

Alternatively, in the case of DMRS configuration type 2, when a single codeword is scheduled for the UE and an antenna port mapped to an index of {2, 10, or 23} is specified, or when two codewords are scheduled for the UE, the UE assumes that any of the remaining orthogonal antenna ports is not associated with PDSCH transmission to another UE.

When the UE receives the PDSCH, it may assume that the precoding granularity P′ is a consecutive resource block in the frequency domain. Here, P′ may correspond to one of {2, 4, wideband}.

When P′ is determined as wideband, the UE does not expect scheduling with non-contiguous PRBs, and may assume that the same precoding is applied to the allocated resources.

On the other hand, when P′ is determined as any one of {2, 4}, a precoding resource block group (PRG) is divided into P′ contiguous PRBs. The number of actually contiguous PRBs in each PRG may be greater than or equal to 1. The UE may assume that the same precoding is applied to contiguous DL PRBs in the PRG.

In order to determine a modulation order, a target code rate, and a transport block size in the PDSCH, the UE first reads the 5-bit MCD field in the DCI, and determines the modulation order and the target code rate. Then, it reads the redundancy version field in the DCI, and determines the redundancy version. Then, the UE determines the transport block size based on the number of layers and the total number of allocated PRBs before rate matching.

FIG. 6 illustrates a procedure in which a UE transmits an uplink (UL) signal to a BS.

Referring to FIG. 6 , the BS schedules UL transmission in relation to, for example, frequency/time resources, a transport layer, a UL precoder, and an MCS (S1501). In particular, the BS may determine, through the above-described operations, a beam for PUSCH transmission of the UE.

The UE receives DCI for UL scheduling (including scheduling information about the PUSCH) from the BS on the PDCCH (S1502).

DCI format 0_0 or 0_1 may be used for UL scheduling. In particular, DCI format 0_1 includes the following information: an identifier for DCI formats, a UL/supplementary UL (SUL), a bandwidth part indicator, frequency domain resource assignment, time domain resource assignment, a frequency hopping flag, a modulation and coding scheme (MCS), an SRS resource indicator (SRI), precoding information and number of layers, antenna port(s), an SRS request, DMRS sequence initialization, and UL shared channel (UL-SCH) indicator.

In particular, SRS resources configured in an SRS resource set associated with the higher layer parameter ‘usage’ may be indicated by the SRS resource indicator field. In addition, ‘spatialRelationInfo’ may be configured for each SRS resource, and the value thereof may be one of {CRI, SSB, SRI}.

The UE transmits UL data to the BS on PUSCH (S1503).

When the UE detects a PDCCH including DCI format 0_0 or 0_1, it transmits the PUSCH according to an indication by the DCI.

For PUSCH transmission, two transmission schemes are supported: codebook-based transmission and non-codebook-based transmission:

i) When the higher layer parameter ‘txConfig’ is set to ‘codebook’, the UE is configured for codebook-based transmission. On the other hand, when the higher layer parameter ‘txConfig’ is set to ‘nonCodebook’, the UE is configured for non-codebook based transmission. When the higher layer parameter ‘txConfig’ is not configured, the UE does not expect scheduling by DCI format 0_1. When the PUSCH is scheduled according to DCI format 0_0, PUSCH transmission is based on a single antenna port.

In the case of codebook-based transmission, the PUSCH may be scheduled by DCI format 0_0 or DCI format 0_1, or scheduled semi-statically. When the PUSCH is scheduled by DCI format 0_1, the UE determines the PUSCH transmission precoder based on the SRI, transmit precoding matrix indicator (TPMI) and transmission rank from the DCI, as given by the SRS resource indicator field and the precoding information and number of layers field. The TPMI is used to indicate a precoder to be applied across antenna ports, and corresponds to an SRS resource selected by the SRI when multiple SRS resources are configured. Alternatively, when a single SRS resource is configured, the TPMI is used to indicate a precoder to be applied across antenna ports, and corresponds to the single SRS resource. A transmission precoder is selected from the UL codebook having the same number of antenna ports as the higher layer parameter ‘nrofSRS-Ports’. When the higher layer in which the UE is set to ‘codebook’ is configured with the parameter ‘txConfig’, at least one SRS resource is configured for the UE. The SRI indicated in slot n is associated with the most recent transmission of the SRS resource identified by the SRI, where the SRS resource precedes the PDCCH carrying the SRI (i.e., slot n).

ii) In the case of non-codebook-based transmission, the PUSCH may be scheduled by DCI format 0_0 or DCI format 0_1, or scheduled semi-statically. When multiple SRS resources are configured, the UE may determine the PUSCH precoder and transmission rank based on the wideband SRI. Here, the SRI is given by the SRS resource indicator in the DCI or by the higher layer parameter ‘srs-ResourceIndicator’. The UE may use one or multiple SRS resources for SRS transmission. Here, the number of SRS resources may be configured for simultaneous transmission within the same RB based on UE capability. Only one SRS port is configured for each SRS resource. Only one SRS resource may be configured by the higher layer parameter ‘usage’ set to ‘nonCodebook’. The maximum number of SRS resources that may be configured for non-codebook-based UL transmission is 4. The SRI indicated in slot n is associated with the most recent transmission of the SRS resource identified by the SRI, where the SRS transmission precedes the PDCCH carrying the SRI (i.e., slot n).

FIG. 7 illustrates an example of time domain resource allocation for a PDSCH by a PDCCH and an example of time domain resource allocation for a PUSCH by a PDCCH.

DCI carried by the PDCCH in order to schedule a PDSCH or a PUSCH includes a (time domain resource assignment, TDRA) field. The TDRA field provides a value m for a row index m+1 to an allocation table for the PDSCH or the PUSCH. Predefined default PDSCH time domain allocation is applied as the allocation table for the PDSCH, or a PDSCH TDRA table that the BS configures through RRC signaled pdsch-TimeDomainAllocationList is applied as the allocation table for the PDSCH. Predefined default PUSCH time domain allocation is applied as the allocation table for the PDSCH, or a PUSCH TDRA table that the BS configures through RRC signaled pusch-TimeDomainAllocationList is applied as the allocation table for the PUSCH. The PDSCH TDRA table to be applied and/or the PUSCH TDRA table to be applied may be determined according a fixed/predefined rule (e.g., refer to 3GPP TS 38.214)

In PDSCH time domain resource configurations, each indexed row defines a DL assignment-to-PDSCH slot offset K₀, a start and length indicator value SLIV (or directly, a start position (e.g., start symbol index S) and an allocation length (e.g., the number of symbols, L) of the PDSCH in a slot), and a PDSCH mapping type. In PUSCH time domain resource configurations, each indexed row defines a UL grant-to-PUSCH slot offset K₂, a start position (e.g., start symbol index S) and an allocation length (e.g., the number of symbols, L) of the PUSCH in a slot, and a PUSCH mapping type. K₀ for the PDSCH and K₂ for the PUSCH indicate the difference between the slot with the PDCCH and the slot with the PDSCH or PUSCH corresponding to the PDCCH. SLIV denotes a joint indicator of the start symbol S relative to the start of the slot with the PDSCH or PUSCH and the number of consecutive symbols, L, counting from the symbol S. The PDSCH/PUSCH mapping type includes two mapping types: one is mapping Type A and the other is mapping Type B. In PDSCH/PUSCH mapping Type A, a demodulation reference signal (DMRS) is located in the third symbol (symbol #2) or fourth symbol (symbol #3) in a slot according to RRC signaling. In PDSCH/PUSCH mapping Type B, the DMRS is located in the first symbol allocated for the PDSCH/PUSCH.

The scheduling DCI includes an FDRA field that provides assignment information about RBs used for the PDSCH or the PUSCH. For example, the FDRA field provides information about a cell for PDSCH or PUSCH transmission, information about a BWP for PDSCH or PUSCH transmission, and/or information about RBs for PDSCH or PUSCH transmission to the UE.

Resource Allocation by RRC

As mentioned above, there are two types of transmission without a dynamic grant: configured grant Type 1 and configured grant Type 2. In configured grant Type 1, a UL grant is provided by RRC signaling and stored as a configured UL grant. In configured grant Type 2, the UL grant is provided by the PDCCH and stored or cleared as the configured UL grant based on L1 signaling indicating configured UL grant activation or deactivation. Type 1 and Type 2 may be configured by RRC signaling per serving cell and per BWP. Multiple configurations may be simultaneously activated on different serving cells.

When configured grant Type 1 is configured, the UE may be provided with the following parameters through RRC signaling:

-   -   cs-RNTI corresponding to a CS-RNTI for retransmission;     -   periodicity corresponding to a periodicity of configured grant         Type 1;     -   timeDomainOffset indicating an offset of a resource with respect         to system frame number (SFN)=0 in the time domain;     -   timeDomainAllocation value m that provides a row index m+1         pointing to the allocation table, indicating a combination of         the start symbol S, the length L, and the PUSCH mapping type;     -   frequencyDomainAllocation that provides frequency domain         resource allocation; and     -   mcsAndTBS that provides I_(MCS) indicating a modulation order, a         target code rate, and a transport block size.

Upon configuration of configured grant Type 1 for a serving cell by RRC, the UE stores the UL grant provided by RRC as a configured UL grant for an indicated serving cell and initializes or re-initializes the configured UL grant to start in a symbol according to timeDomainOffset and S (derived from SLIV) and to recur with periodicity. After the UL grant is configured for configured grant Type 1, the UE may consider that the UL grant recurs in association with each symbol satisfying: [(SFN*numberOfslotsPerFrame (numberOfSymbolsPerSlot)+(slot number in the frame*numberOfSymbolsPerSlot)+symbol number in the slot]=(timeDomainOffset*numberOfSymbolsPerSlot+S+N*periodicity) modulo (1024*numberOfSlotsPerFrame*numberOfSymbolsPerSlot), for all N>=0, where numberOfSlotsPerFrame and numberOfSymbolsPerSlot indicate the number of consecutive slots per frame and consecutive OFDM symbols per slot.

For configured grant Type 2, the UE may be provided with the following parameters by the BS through RRC signaling:

-   -   cs-RNTI corresponding to a CS-RNTI for activation, deactivation,         and retransmission; and     -   periodicity that provides a periodicity of configured grant Type         2.

An actual UL grant is provided to the UE by the PDCCH (addressed to the CS-RNTI). After the UL grant is configured for configured grant Type 2, the UE may consider that the UL grant recurs in association with each symbol satisfying: [(SFN*numberOfSlotsPerFrame*numberOfSymbolsPerSlot)+(slot number in the frame*numberOfSymbolsPerSlot)+symbol number in the slot]=[(SFN_(start time)*numberOfSlotsPerFrame*numberOfSymbolsPerSlot+slot_(start time)*numberOfSymbolsPerSlot+symbol_(start time))+N*periodicity] modulo (1024*numberOfSlotsPerFrame*numberOfSymbolsPerSlot), for all N>=0, where SFN_(start time), slot_(start time), and symbol_(start time) represent an SFN, a slot, and a symbol, respectively, of the first transmission opportunity of the PUSCH after the configured grant is (re-)initialized, and numberOfSlotsPerFrame and numberOfSymbolsPerSlot indicate the number of consecutive slots per frame and consecutive OFDM symbols per slot, respectively.

On DL, the UE may be configured with SPS per serving cell and per BWP by RRC signaling from the BS. For DL SPS, DL assignment is provided to the UE by the PDCCH and stored or cleared based on L1 signaling indicating SPS activation or deactivation. When SPS is configured, the UE may be provided with the following parameters by the BS through RRC signaling:

-   -   cs-RNTI corresponding to a CS-RNTI for activation, deactivation,         and retransmission;     -   nrofHARQ-Processes that provides the number of HARQ processes         for SPS; and     -   periodicity that provides a periodicity of configured DL         assignment for SPS.

After DL assignment is configured for SPS, the UE may consider sequentially that N-th DL assignment occurs in a slot satisfying: (numberOfSlotsPerFrame*SFN+slot number in the frame)=[(numberOfSlotsPerFrame*SFN_(start time)+slot_(start time))+N*periodicity*numberOfSlotsPerFrame/10] modulo (1024*numberOfSlotsPerFrame), where SFN_(start time) and slot_(start time) represent an SFN and a slot, respectively, of first transmission of the PDSCH after configured DL assignment is (re-)initialized, and numberOfSlotsPerFrame and numberOfSymbolsPerSlot indicate the number of consecutive slots per frame and consecutive OFDM symbols per slot, respectively.

If the CRC of a corresponding DCI format is scrambled with the CS-RNTI provided by the RRC parameter cs-RNTI, and a new data indicator field for an enabled transport block is set to 0, the UE validates, for scheduling activation or scheduling release, a DL SPS assignment PDCCH or a configured UL grant Type 2 PDCCH. Validation of the DCI format is achieved if all fields for the DCI format are set. An example of special fields for DL SPS and UL grant Type 2 scheduling activation PDCCH validation, and an example of special fields for DL SPS and UL grant Type 2 scheduling release PDCCH validation.

FIG. 8 is a diagram illustrating a HARQ-ACK operation in relation to operation of a UE for reporting control information.

First, HARQ in NR may have the following characteristics (hereinafter, H-1 and H-2).

-   -   H-1) 1-bit HARQ-ACK feedback per transport block (TB) may be         supported. Here, the operation of one DL HARQ process is         supported for some UEs, whereas the operation of one or more DL         HARQ processes is supported for a given UE.     -   H-2) The UE may support a set of minimum HARQ processing times.         Here, the minimum HARQ processing time means a minimum required         time until a corresponding HARQ-ACK transmission timing from a         timing when the UE receives DL data from the BS. In this regard,         two UE processing times N1 and K1 may be defined according         to (1) symbol granularity and (2) slot granularity. Here, K1 may         represent the number of slots from a PDSCH slot to a         corresponding HARQ-ACK transmission slot.

First, from the viewpoint of the UE, N1 represents the number of OFDM symbols required for UE processing from the end of PDSCH reception to the earliest possible start of corresponding HARQ-ACK transmission. N1 may be defined as shown in Tables 5 and 6 below according to OFDM numerology (i.e., subcarrier spacing) and a DMRS pattern.

TABLE 5 HARQ 15 30 60 120 Timing KHz KHz KHz KHz Configuration Parameter Units SCS SCS SCS SCS Front-loaded N1 Symbols  8 10 17 20 DMRS only Front-loaded N1 Symbols 13 13 20 24 DMRS only + additional DMRS

TABLE 6 HARQ Timing 15 KHz 30 KHz 60 KHz Configuration Parameter Units SCS SCS SCS Front-loaded N1 Symbols  3   4.5 9(FR1) DMRS only Front-loaded N1 Symbols [13] [13] [20] DMRS only + additional DMRS

Referring to FIG. 8 , a HARQ-ACK timing K1 may indicate the number of slots from a PDSCH slot to a corresponding HARQ-ACK transmission slot. K0 represents the number of slots from a slot with a DL grant PDCCH to a slot with corresponding PDSCH transmission, and K2 represents the number of slots from a slot with a UL grant PDCCH to a slot with corresponding PUSCH transmission. That is, KO, K1, and K2 may be briefly summarized as shown in Table 7 below.

TABLE 7 A B K0 DL scheduling DCI Corresponding DL data transmission K1 DL data reception Corresponding HARQ-ACK K2 UL scheduling DCI Corresponding UL data transmission

A slot timing between A and B is indicated by a field in DCI from a set of values. In addition, NR supports different minimum HARQ processing times between UEs. The HARQ processing time includes a delay between a DL data reception timing and a corresponding HARQ-ACK transmission timing and a delay between a UL grant reception timing and a corresponding UL data transmission timing. The UE transmits the capability of a minimum HARQ processing time thereof to the BS. Asynchronous and adaptive DL HARQ is supported at least in enhanced mobile broadband (eMBB) and ultra-reliable low latency (URLLC).

From the viewpoint of the UE, HARQ ACK/NACK feedback for multiple DL transmissions in the time domain may be transmitted in one UL data/control domain. A timing between DL data reception and corresponding acknowledgment is indicated by a field in DCI from a set of values, and the set of values is configured by a higher layer. The timing is defined at least for the case in which the timing is not known to the UE.

Non-Terrestrial Networks Reference

FIG. 9 illustrates a non-terrestrial network (NTN).

A non-terrestrial network (NTN) refers to a wireless network configured using satellites (e.g., geostationary earth orbit satellites (GEO)/low-earth orbit satellites (LEO)). Based on the NTN, coverage may be extended and a highly reliable network service may be provided. For example, the NTN may be configured alone, or may be combined with a conventional terrestrial network to configure a wireless communication system. For example, in the NTN network, i) a link between a satellite and a UE, ii) a link between satellites, iii) a link between a satellite and a gateway, and the like may be configured.

The following terms may be used to describe the configuration of a wireless communication system employing satellites.

-   -   Satellite: a space-borne vehicle embarking a bent pipe payload         or a regenerative payload telecommunication transmitter, placed         into Low-Earth Orbit (LEO) typically at an altitude between 500         km to 2000 km, Medium-Earth Orbit (MEO) typically at an altitude         between 8000 to 20000 lm, or Geostationary satellite Earth Orbit         (GEO) at 35 786 km altitude.     -   Satellite network: Network, or segments of network, using a         space-borne vehicle to embark a transmission equipment relay         node or base station.     -   Satellite RAT: a RAT defined to support at least one satellite.     -   5G Satellite RAT: a Satellite RAT defined as part of the New         Radio.     -   5G satellite access network: 5G access network using at least         one satellite.     -   Terrestrial: located at the surface of Earth.     -   Terrestrial network: Network, or segments of a network located         at the surface of the Earth.

Use cases that may be provided by a communication system employing a satellite connection may be divided into three categories. The “Service Continuity” category may be used to provide network connectivity in geographic areas where 5G services cannot be accessed through the wireless coverage of terrestrial networks. For example, a satellite connection may be used for a UE associated with a pedestrian user or a UE on a moving land-based platform (e.g., car, coach, truck, train), air platform (e.g., commercial or private jet) or marine platform (e.g., marine vessel). In the “Service Ubiquity” category, when terrestrial networks are unavailable (due to, for example, disaster, destruction, economic situations, etc.), satellite connections may be used for IOT/public safety-related emergency networks/home access, etc. The “Service Scalability” category includes services using wide coverage of satellite networks.

For example, a 5G satellite access network may be connected to a 5G core Network. In this case, the satellite may be a bent pipe satellite or a regenerative satellite. The NR radio protocols may be used between the UE and the satellite. Also, F1 interface may be used between the satellite and the gNB.

As described above, a non-terrestrial network (NTN) refers to a wireless network configured using a device that is not fixed on the ground, such as satellite. A representative example is a satellite network. Based on the NTN, coverage may be extended and a highly reliable network service may be provided. For example, the NTN may be configured alone, or may be combined with an existing terrestrial network to configure a wireless communication system.

Use cases that may be provided by a communication system employing an NTN may be divided into three categories. The “Service Continuity” category may be used to provide network connectivity in geographic areas where 5G services cannot be accessed through the wireless coverage of terrestrial networks. For example, a satellite connection may be used for a UE associated with a pedestrian user or a UE on a moving land-based platform (e.g., car, coach, truck, train), air platform (e.g., commercial or private jet) or marine platform (e.g., marine vessel). In the “Service Ubiquity” category, when terrestrial networks are unavailable (due to, for example, disaster, destruction, economic situations, etc.), satellite connections may be used for IOT/public safety-related emergency networks/home access, etc. The “Service Scalability” category includes services using wide coverage of satellite networks.

Referring to FIG. 9 , the NTN includes one or more satellites 410, one or more NTN gateways 420 capable of communicating with the satellites, and one or more UEs (/BSs) 430 capable of receiving mobile satellite services from the satellites. For simplicity, the description is focused on the example of the NTN including satellites, but is not intended to limit the scope of the present disclosure. Accordingly, the NTN may include not only the satellites, but also aerial vehicles (Unmanned Aircraft Systems (UAS) encompassing tethered UAS (TUA), Lighter than Air UAS (LTA), Heavier than Air UAS (HTA), all operating in altitudes typically between 8 and 50 km including High Altitude Platforms (HAPs)).

The satellite 410 is a space-borne vehicle equipped with a bent pipe payload or a regenerative payload telecommunication transmitter and may be located in a low earth orbit (LEO), a medium earth orbit (MEO), or a geostationary earth orbit (GEO). The NTN gateway 420 is an earth station or gateway existing on the surface of the earth, and provides sufficient RF power/sensitivity to access the satellite. The NTN gateway corresponds to a transport network layer (TNL) node.

The NTN may have i) a link between a satellite and a UE, ii) a link between satellites, iii) a link between a satellite and an NTN gateway. A service link refers to a radio link between a satellite and a UE. Inter-satellite links (ISLs) between satellites may be present when there are multiple satellites. A feeder link refers to a radio link between an NTN gateway and a satellite (or UAS platform). The gateway may be connected to a data network and may communicate with a satellite through the feeder link. The UE may communicate via the satellite and service link.

As NTN operation scenarios, two scenarios which are based on transparent payload and regenerative payload, respectively may be considered. FIG. 9 -(a) shows an example of a scenario based on a transparent payload. In the scenario based on the transparent payload, the signal repeated by the payload is not changed. The satellites 410 repeat the NR-Uu radio interface from the feeder link to the service link (or vice versa), and the satellite radio interface (SRI) on the feeder link is NR-Uu. The NTN gateway 420 supports all functions necessary to transfer the signal of the NR-Uu interface. Also, different transparent satellites may be connected to the same gNB on the ground. FIG. 9 -(b) shows an example of a scenario based on a regenerative payload. In the scenario based on the regenerative payload, the satellite 410 may perform some or all of the functions of a conventional BS (e.g., gNB), and may thus perform some or all of frequency conversion/demodulation/decoding/modulation. The service link between the UE and a satellite is established using the NR-Uu radio interface, and the feeder link between the NTN gateway and a satellite is established using the satellite radio interface (SRI). The SRI corresponds to a transport link between the NTN gateway and the satellite.

The UE 430 may be connected to 5GCN through an NTN-based NG-RAN and a conventional cellular NG-RAN simultaneously. Alternatively, the UE may be connected to the 5GCN via two or more NTNs (e.g., LEO NTN and GEO NTN, etc.) simultaneously.

FIG. 10 illustrates an overview and a scenario of an NTN.

NTN refers to a network or network segment in which a satellite (or UAS platform) uses RF resources. Typical scenarios of the NTN providing access to a UE include an NTN scenario based on a transparent payload as shown in FIG. 10 -(a) and an NTN scenario based on a regenerative payload as shown in FIG. 10 -(b).

NTN typically features the following elements,

-   -   One or several sat-gateways that connect the Non-Terrestrial         Network to a public data network     -   A GEO satellite is fed by one or several sat-gateways which are         deployed across the satellite targeted coverage (e.g. regional         or even continental coverage). We assume that UE in a cell are         served by only one sat-gateway.     -   A non-GEO satellite served successively by one or several         sat-gateways at a time. The system ensures service and feeder         link continuity between the successive serving sat-gateways with         sufficient time duration to proceed with mobility anchoring and         hand-over.     -   A feeder link or radio link between a sat-gateway and the         satellite (or UAS platform)     -   A service link or radio link between the user equipment and the         satellite (or UAS platform).     -   A satellite (or UAS platform) which may implement either a         transparent or a regenerative (with on board processing)         payload. The satellite (or UAS platform) generate beams         typically generate several beams over a given service area         bounded by its field of view. The footprints of the beams are         typically of elliptic shape. The field of view of a satellites         (or UAS platforms) depends on the on board antenna diagram and         min elevation angle.     -   A transparent payload: Radio Frequency filtering, Frequency         conversion and amplification. Hence, the waveform signal         repeated by the payload is un-changed;     -   A regenerative payload: Radio Frequency filtering, Frequency         conversion and amplification as well as demodulation/decoding,         switch and/or routing, coding/modulation. This is effectively         equivalent to having all or part of base station functions (e.g.         gNB) on board the satellite (or UAS platform).     -   Inter-satellite links (ISL) optionally in case of a         constellation of satellites. This will require regenerative         payloads on board the satellites. ISL may operate in RF         frequency or optical bands.     -   User Equipment is served by the satellite (or UAS platform)         within the targeted service area.

Table 8 below defines various types of satellites (or UAS platforms).

TABLE 8 Typical beam Platforms Altitude range Orbit footprint size Low-Earth Orbit 300-1500 km Circular around 100-1000 km (LEO) satellite the earth Medium-Earth Orbit 7000-25000 km 100-1000 km (MEO) satellite Geostationary Earth 35 786 km notional station 200-3500 km Orbit (GEO) satellite keeping position UAS platform 8-50 km fixed in terms of 5-200 km (including HAPS) (20 km for HAPS) elevation/azimuth with respect to a given earth point High Elliptical Orbit 400-50000 km Elliptical around 200-3500 km (HEO) satellite the earth

Typically, GEO satellite and UAS are used to provide continental, regional or local service. A constellation of LEO and MEO is used to provide services in both Northern and Southern hemispheres. In some case, the constellation can even provide global coverage including polar regions. For the later, this requires appropriate orbit inclination, sufficient beams generated and inter-satellite links. HEO satellite systems are not considered in this document.

An NTN that provides access to a terminal in six reference scenarios described below can be considered.

-   -   Circular orbiting and notional station keeping platforms.     -   Highest RTD constraint     -   Highest Doppler constraint     -   A transparent and a regenerative payload     -   One ISL case and one without ISL. Regenerative payload is         mandatory in the case of inter-satellite links.     -   Fixed or steerable beams resulting respectively in moving or         fixed beam foot print on the ground

Six scenarios are considered as depicted in Table 9 and are detailed in Table 10.

TABLE 9 Transparent Regenerative satellite satellite GEO based non-terrestrial access network Scenario A Scenario B LEO based non-terrestrial access network: Scenario C1 Scenario D1 steerable beams LEO based non-terrestrial access network: Scenario C2 Scenario D2 the beams move with the satellite

TABLE 10 GEO based non-terrestrial LEO based non-terrestrial Scenarios access network (Scenario A and B) access network (Scenario C & D) Orbit type notional station keeping position circular orbiting around the fixed in terms of elevation/azimuth earth with respect to a given earth point Altitude 35,786 km 600 km 1,200 km Spectrum (service link) <6 GHz (e.g. 2 GHz) >6 GHz (e.g. DL 20 GHz, UL 30 GHz) Max channel bandwidth 30 MHz for band <6 GHz capability (service link) 1 GHz for band >6 GHz Payload Scenario A: Transparent Scenario C: Transparent (including radio frequency (including radio frequency function only) function only) Scenario B: regenerative Scenario D: Regenerative (including all or part of RAN (including all or part of RAN functions) functions) Inter-Satellite link No Scenario C: No Scenario D: Yes/No (Both cases are possible.) Earth-fixed beams Yes Scenario C1: Yes (steerable beams), see note 1 Scenario C2: No (the beams move with the satellite) Scenario D 1: Yes (steerable beams), see note 1 Scenario D 2: No (the beams move with the satellite) Max beam foot print size 3500 km (Note 5) 1000 km (edge to edge) regardless of the elevation angle Min Elevation angle for 10° for service link and 10° 10° for service link and 10° both sat-gateway and for feeder link for feeder link user equipment Max distance between 40,581 km 1,932 km (600 km altitude) satellite and user 3,131 km (1,200 km altitude) equipment at min elevation angle Max Round Trip Delay Scenario A: 541.46 ms (service and Scenario C: (transparent (propagation delay only) feeder links) payload: service and feeder Scenario B: 270.73 ms (service link links) only) 25.77 ms (600 km) 41.77 ms (1200 km) Scenario D: (regenerative payload: service link only) 12.89 ms (600 km) 20.89 ms (1200 km) Max differential delay 10.3 ms 3.12 ms and 3.18 ms for within a cell (Note 6) respectively 600 km and 1200 km Max Doppler shift (earth 0.93 ppm 24 ppm (600 km) fixed user equipment) 21 ppm(1200 km) Max Doppler shift 0.000 045 ppm/s 0.27 ppm/s (600 km) variation (earth fixed 0.13 ppm/s(1200 km) user equipment) User equipment motion 1200 km/h (e.g. aircraft) 500 km/h (e.g. high on the earth speed train) Possibly 1200 km/h (e.g. aircraft) User equipment antenna Omnidirectional antenna (linear polarisation), assuming 0 dBi types Directive antenna (up to 60 cm equivalent aperture diameter in circular polarisation) User equipment Tx Omnidirectional antenna: UE power class 3 with up to 200 mW power Directive antenna: up to 20 W User equipment Noise Omnidirectional antenna: 7 dB figure Directive antenna: 1.2 dB Service link 3GPP defined New Radio Feeder link 3GPP or non-3GPP defined 3GPP or non-3GPP defined Radio interface Radio interface note 1: Each satellite has the capability to steer beams towards fixed points on earth using beamforming techniques. This is applicable for a period of time corresponding to the visibility time of the satellite NOTE 2: Max delay variation within a beam (earth fixed user equipment) is calculated based on Min Elevation angle for both gateway and user equipment NOTE 3: Max differential delay within a beam is calculated based on Max beam foot print diameter at nadir NOTE 4: Speed of light used for delay calculation is 299792458 m/s. (Note 5): The Maximum beam foot print size for GEO is based on current state of the art GEO High Throughput systems, assuming either spot beams at the edge of coverage (low elevation). (Note 6): The maximum differential delay at cell level has been computed considering the one at beam level for largest beam size. It doesn't preclude that cell may include more than one beam when beam size are small or medium size. However the cumulated differential delay of all beams within a cell will not exceed the maximum differential delay at cell level in the table above.

The NTN study results apply to GEO scenarios as well as all NGSO scenarios with circular orbit at altitude greater than or equal to 600 km.

Hereinafter, the NTN reference point will be described.

FIG. 11 illustrates TA components of the NTN. Here, the TA offset (NTAoffset) may not be plotted.

With consideration on the larger cell coverage, long round trip time (RTT) and high Doppler, enhancements are considered to ensure the performance for timing and frequency synchronization for UL transmission.

Referring to FIG. 11 , a reference point related to timing advance (TA) of initial access and subsequent TA maintenance/management is illustrated. Terms defined in relation to FIG. 11 are described below.

Option 1: Autonomous Acquisition of the TA at UE with UE Known Location and Satellite Ephemeris.

Regarding option 1, the required TA value for UL transmission including PRACH can be calculated by the UE. The corresponding adjustment can be done, either with UE-specific differential TA or full TA (consisting of UE specific differential TA and common TA).

W.r.t the full TA compensation at the UE side, both the alignment on the UL timing among UEs and DL and UL frame timing at network side can be achieved. However, in case of satellite with transparent payload, further discussion on how to handle the impact introduced by feeder link will be conducted in normative work. Additional needs for the network to manage the timing offset between the DL and UL frame timing can be considered, if impacts introduced by feeder link is not compensated by UE in corresponding compensation.

W.r.t the UE specific differential TA only, additional indication on a single reference point should be signalled to UEs per beam/cell for achieving the UL timing alignment among UEs within the coverage of the same beam/cell. Timing offset between DL and UL frame timing at the network side should also be managed by the network regardless of the satellite payload type.

With concern on the accuracy on the self-calculated TA value at the UE side, additional TA signalling from network to UE for TA refinement, e.g., during initial access and/or TA maintenance, can be determined in the normative work.

Option 2: Timing Advanced Adjustment Based on Network Indication

Regarding option 2, the common TA, which refers to the common component of propagation delay shared by all UEs within the coverage of same satellite beam/cell, is broadcasted by the network per satellite beam/cell. The calculation of this common TA is conducted by the network with assumption on at least a single reference point per satellite beam/cell.

The indication for UE-specific differential TA from network as the Rel-15 TA mechanism is also needed. For satisfying the larger coverage of NTN, extension of value range for TA indication in RAR, either explicitly or implicitly, is identified. Whether to support negative TA value in corresponding indication will be determined in the normative phase. Moreover, indication of timing drift rate, from the network to UE, is also supported to enable the TA adjustment at UE side.

For calculation of common TA in the above two options, single reference point per beam is considered as the baseline. Whether and how to support the multiple reference points can be further discussed in the normative work.

For the UL frequency compensation, at least for LEO system, the following solutions are identified with consideration on the beam specific post-compensation of common frequency offset at the network side:

-   -   Regarding option 1, both the estimation and pre-compensation of         UE-specific frequency offset are conducted at the UE side. The         acquisition of this value can be done by utilizing DL reference         signals, UE location and satellite ephemeris.     -   Regarding option 2, the required frequency offset for UL         frequency compensation at least in LEO systems is indicated by         the network to UE. The acquisition on this value can be done at         the network side with detection of UL signals, e.g., preamble.

Indication of compensated frequency offset values by the network is also supported in case that compensation of the frequency offset is conducted by the network in the uplink and/or the downlink respectively. However, indication of Doppler drift rate is not necessary.

Hereinafter, more delay-tolerant re-transmission mechanisms will be described in detail.

As follows, two main aspects of a retransmission mechanism with improved delay tolerance can be discussed.

-   -   Disabling of HARQ in NR NTN     -   HARQ optimization in NR-NTN

HARQ Round Trip Time in NR is of the order of several ms. The propagation delays in NTN are much longer, ranging from several milliseconds to hundreds of milliseconds depending on the satellite orbit. The HARQ RTT can be much longer in NTN. It was identified early in the study phase that there would be a need to discuss potential impact and solutions on HARQ procedure. RAN1 has focused on physical layer aspects while RAN2 has focused on MAC layer aspects.

In this regard, disabling of HARQ in NR NTN may be considered.

It was discussed that when UL HARQ feedback is disabled, there could be issues if (i) MAC CE and RRC signalling are not received by UE, or (ii) DL packets not correctly received by UE for a long period of time without gNB knowing it.

The following were discussed without convergence on the necessity of introducing such solutions for NTN when HARQ feedback is disabled

-   -   (1) Indicate HARQ disabling via DCI in new/re-interpreted field     -   (2) New UCI feedback for reporting DL transmission disruption         and or requesting DL scheduling changes

The following possible enhancements for slot-aggregation or blind repetitions were considered. There is no convergence on the necessity of introducing such enhancements for NTN.

-   -   (1) Greater than 8 slot-aggregation     -   (2) Time-interleaved slot aggregation     -   (3) New MCS table

Next, a method for optimizing HARQ for the NR NTN will be described.

Solutions to avoid reduction in peak data rates in NTN were discussed. One solution is to increase the number of HARQ processes to match the longer satellite round trip delay to avoid stop-and-wait in HARQ procedure. Another solution is to disable UL HARQ feedback to avoid stop-and-wait in HARQ procedure and rely on RLC ARQ for reliability. The throughput performance for both types of solutions was evaluated at link level and system level by several contributing companies.

The observations from the evaluations performed on the effect of the number of HARQ processes on performance are summarized as follows:

-   -   Three sources provided link-level simulations of throughput         versus SNR with the following observations:         -   One source simulated with a TDL-D suburban channel with             elevation angle of 30 degrees with BLER target of 1% for RLC             ARQ with 16 HARQ processes, and BLER targets 1% and 10% with             32/64/128/256 HARQ processes. There was no observable gain             in throughput with increased number of HARQ processes             compared to RLC layer re-transmission with RTT in {32, 64,             128, 256} ms.         -   One source simulated with a TDL-D suburban channel with             elevation angle of 30 degrees with BLER targets of 0.1% for             RLC ARQ with 16 HARQ processes, and BLER targets 1% and 10%             with 32 HARQ processes. An average throughput gain of 10%             was observed with 32 HARQ processes compared to RLC ARQ with             16 HARQ processes with RTT=32 ms.         -   One source provides the simulation results in following             cases with RTT=32 ms, e.g., assuming BLER targets at 1% for             RLC ARQ with 16 HARQ processes, BLER targets 1% and 10% with             32 HARQ processes. There is no observable gain in throughput             with 32 HARQ processes compared to RLC ARQ with 16 HARQ             processes in case that channel is assumed as TDL-D with             delay spread/K-factor taken from system channel model in             suburban scenario with elevation angle 30. Performance gain             can be observed with other channels, especially, up to 12.5%             spectral efficiency gain is achieved in case that channel is             assumed as TDL-A in suburban with 30° elevation angle.             Moreover, simulation based on the simulation with             consideration on other scheduling operations: (i) additional             MCS offset, (ii) MCS table based on lower efficiency (iii)             slot aggregation with different BLER targets are conducted.             Significant gain can be observed with enlarging the HARQ             process number.

One source provided system level simulations for LEO=1200 km with 20% resource utilization, 16 and 32 HARQ processes, 15 and 20 UEs per cell, proportional fair scheduling, and no frequency re-use. The spectral efficiency gain per user with 32 HARQ processes compared to 16 HARQ processes depends on the number of UEs. With 15 UEs per beam, an average spectral efficiency gain of 12% at 50% per centile is observed. With 20 UEs per cell there is no observable gain.

The following options were considered with no convergence on which option to choose:

-   -   Option A: Keep 16 HARQ process IDs and rely on RLC ARQ for HARQ         processes with UL HARQ feedback disabled via RRC     -   Option B: Greater than 16 HARQ process IDs with UL HARQ feedback         enabled via RRC with following consideration. In this case, in         the case of 16 or more HARQ process IDs, maintenance of a 4-bit         HARQ process ID field in UE capability and DCI may be         considered.

Alternatively, the following solutions may be considered for 16 or more HARQ processes keeping the 4-bit HARQ process ID field in DCI:

-   -   Slot number based     -   Virtual process ID based with HARQ re-transmission timing         restrictions     -   Reuse HARQ process ID within RTD (time window)     -   Re-interpretation of existing DCI fields with assistance         information from higher layers     -   One source also considered solutions where the HARQ process ID         field is increased beyond 4 bits

With regards to HARQ enhancements for soft buffer management and stop-and-wait time reduction, the following options were considered with no convergence on which, if any, of the options, to choose:

-   -   Option A-1: Pre-active/pre-emptive HARQ to reduce stop-and-wait         time     -   Option A-2: Enabling/disabling of HARQ buffer usage configurable         on a per UE and per HARQ process     -   Option A-3: HARQ buffer status report from the UE

The number of HARQ processes with additional considerations for HARQ feedback, HARQ buffer size, RLC feedback, and RLC ARQ buffer size should be discussed further when specifications are developed.

The configurations (NR frame structure, NTN system, etc.) discussed above may be combined and applied in the contents described below, or may be supplemented to clarify the technical features of the methods proposed in the present disclosure. In addition, methods related to HARQ disabling, which will be described later, are related to UL transmission and may be equally applied to the DL signal transmission method in the NR system or LTE system described above. It is to be noted that terms, expressions, structures, and the like defined in each system may be appropriately modified or replaced so that the technical idea proposed in this specification can be implemented in the corresponding system.

HARQ Disabling in NTN

As described above, an NR NTN and/or LTE NTN service may be considered to secure wider coverage or to provide a wireless communication service in a place in which it is not easy to install a wireless communication BS. The NTN service may be a service that provides the wireless communication service to UEs by installing the BS in places that are not located on the ground, such as satellites (GEO, LEO, and MEO satellites), airplanes, unmanned aerial vehicles, drones, etc., instead of installing the BS on the ground. In this case, a latency problem may occur due to delay when the UE performs HARQ feedback.

Hereinafter, an effective HARQ feedback enabling/disabling technique will be described.

A frequency band used for the NR NTN service mainly considers a 2-GHz band (S-band: 2 to 4 GHz) in a band below 6 GHz, and a DL 20-GHz band and a UL 30-GHz band (Ka-band: 26.5 to 40 GHz) in a band above 6 GHz.

Table 11 below summarizes the contents of maximum roundtrip delay for each scenario described in Table 10 above.

TABLE 11 GEO based non-terrestrial LEO based non-terrestrial Scenarios access network (Scenario A and B) access network (Scenario C & D) Orbit type notional station keeping position fixed circular orbiting around in terms of elevation/azimuth with the earth respect to a given earth point Altitude 35,786 km 600 km 1,200 km Max beam foot print size 3500 km (Note 5) 1000 km (edge to edge) regardless of the elevation angle Min Elevation angle for 10° for service link and 10° 10° for service link and 10° both sat-gateway and user for feeder link for feeder link equipment Max distance between 40,581 km 1,932 km (600 km altitude) satellite and user equipment 3,131 km (1,200 km altitude) at min elevation angle Max Round Trip Delay Scenario A: 541.46 ms (service and Scenario C: (transparent (propagation delay only) feeder links) payload: service and Scenario B: 270.73 ms (service link feeder links) only) 25.77 ms (600 km) 41.77 ms (1200 km) Scenario D: (regenerative payload: service link only) 12.89 ms (600 km) 20.89 ms (1200 km)

As shown in Table 11, in the worst case delay (GEO scenario A), a maximum delay may be 540 ms. In this case, when the UE performs HARQ feedback, there is a possibility that a problem of latency will arise due to an additional delay. For this reason, the following scenarios related to HARQ disabling may be considered.

-   -   In a scenario, activation/deactivation of HARQ feedback may be         configured for each UE and each HARQ process.

Based on the above-described scenario, an effective HARQ feedback enabling/disabling technique will be described in detail.

1. Proposal 1: DCI Format Configuration Method

Table 12 below defines DCI format 1_0, and Table 13 defines DCI format 1_1. In DCI format 1_0 and DCI format 1_1, parts related to HARQ feedback are indicated by separate underlines in Tables 12 and 13 below. For example, the parts related to HARQ feedback in DCI format 1_0 and DCI format 1_1 may include a new data indicator (NDI), a redundancy version (RV), a HARQ process number, a downlink assignment index, a TPC command for a scheduled PUCCH, a PUCCH resource indicator, and/or a PDSCH-to-HARQ_feedback timing indicator.

TABLE 12 Field (Item) Bits Identifier for DCI formats 1 Frequency domain resource assignment Variable Time domain resource assignment 4 VRB-to-PRB mapping 1 Modulation and coding scheme 5 New data indicator 1 Redundancy version 2 HARQ process number 4 Downlink assignment index 2 TPC command for 2 scheduled PUCCH PUCCH resource indicator 3 PDSCH-to-HARQ feedback 3 timing indicator

TABLE 13 Field Bits Carrier indicator 0, 3 Identifier for DCI formats 1 Bandwidth part indicator 0, 1, 2 Frequency domain resource assignment Variable Time domain resource assignment 4 VRB-to-PRB mapping 0, 1 PRB bundling size indicator 0, 1 Rate matching indicator 0, 1, 2 ZP CSI-RS Trigger 0, 1, 2 Modulation and coding scheme [TB1] 5 New data indicator [TB1] 1 Redundancy version [TB1] 2 Modulation and coding scheme [TB2] 5 New data indicator [TB2] 1 Redundancy version [TB2] 2 HARQ process number 4 Downlink assignment index 0, 2, 4 TPC command for scheduled PUCCH 2 PUCCH resource indicator 2 PDSCH-to-HARQ feedback 0, 1, 2, 3 timing indicator Antenna port(s) and number of layers 4, 5, 6 Transmission configuration indication 0, 3 SRS request 2 CBG transmission information(CBGTI) 0, 2, 4, 6, 8 CBG flushing out information(CBGFI) 0, 1 DMRS sequence initialization 1

In case of HARQ disabling, all or some of fields (an NVI, an RV, a HARQ process number, a downlink assignment index, a TPC command for scheduled PUCCH, a PUCCH resource indicator, and/or a PDSCH-to-HARQ_feedback timing indicator) in the separately marked DCI formats may be omitted. In other words, all or some of main fields related to a PUCCH and HARQ may be omitted to configure compact DCI. In this case, the following alternatives (Option A-1, Option A-2, and/or Option A-3) may be considered for a compact DCI configuration.

(1) Option A-1

A DCI format, monitored in a common search space (CSS), or DCI format 1_0 may use a compact DCI format. Meanwhile, in a DCI format, monitored in a user search space (USS), or DCI format 1_0, a non-compact DCI format may be configured as a default value, and whether the compact DCI format is used may be configured for the UE. This is because the DCI format monitored in the CSS (i.e., a DCI format for scheduling a system information block (SIB)/paging/random access response (RAR)/Msg4) or DCI format 1_0 desirably requires compact design to increase reliability. In other words, whether to configure the compact DCI format may be determined based on at least one of a DCI format or the type of a search space (e.g., CSS/USS) in which a DCI format is monitored.

(2) Option A-2

As a modified example of Option A-1 described above, in the case of the DCI format, monitored in the CSS, or DCI format 1_0, HARQ feedback may be enabled by default. In this case, a HARQ process id field may be fixed to a specific value (e.g., 0) and may be omitted.

(3) Option A-3

A DCI format may be configured according to whether the UE has a soft buffer combining capability. For example, a field constituting DCI may be determined (e.g., which field is to be omitted may be determined) based on whether HARQ feedback is disabled/enabled and whether data retransmission is supported.

A field in the DCI may be differently configured or determined based on each of the following first case, second case, and third case.

First Case: Case in which HARQ Feedback is Disabled and Data Retransmission is Supported

In the first case, lower 4 or 5 fields (e.g., the downlink assignment index, the TPC command for a scheduled PUCCH, the PUCCH resource indicator, and the HARQ feedback timing indicator (or the PDSCH-to-HARQ_feedback timing indicator), and [HARQ process number]) may be omitted. Meanwhile, in order to distinguish between a retransmission target TB and the RV (and/or the HARQ process ID), the NDI field and/or the RV (and/or the HARQ process ID) field may be configured in a format included in the DCI.

In other words, in the first case, the DCI may exclude the downlink assignment index field, the TPC command field for a scheduled PUCCH, the PUCCH resource indicator field, and/or the HARQ feedback timing indicator (or the PDSCH-to-HARQ_feedback timing indicator) field and include the retransmission target TB field, the NDI field, and/or the RV (and/or HARQ process ID) field. Meanwhile, whether the HARQ process ID field is required or not may be determined according to whether a scheduling operation is supported while interlacing a plurality of TBs before retransmission.

Second Case: Case in which HARQ Feedback is Disabled and Data Retransmission is not Supported

In the second case, the DCI may exclude all of the lower 7 fields separately marked in Table 12 or 13. That is, the downlink assignment index field, the TPC command for a scheduled PUCCH field, the PUCCH resource indicator field, the HARQ feedback timing indicator (or PDSCH-to-HARQ_feedback timing indicator) field, the HARQ process number field, the RV field, and the NDI field may be omitted from the DCI.

Third Case: Case in which HARQ Feedback is Enabled and Data Retransmission is not Supported

Alternatively, in the third case, DCI in which all or some of the HARQ process number field, the RV field, and the NDI field are omitted may be configured. In this case, a new TB may be transmitted in a failed TB (e.g., when NACK is reported).

2. Proposal 2 (DCI Interpretation Method According to HARQ Disabling Method)

(1) First DCI Interpretation Method—Case in which HARQ-Enabled/Disabled is Indicated Through RRC

The first DCI interpretation method may be a method of interpreting DCI when a configuration related to HARQ feedback-disabled is semi-statically configured through RRC with respect to each HARQ process. For example, when HARQ feedback-disabled is configured through RRC, HARQ feedback-disabled may be configured for each cell group (CG). Alternatively, whether to feed back HARQ for each CG may be configured through RRC (refer to REL-16 multiple CGs).

For example, a first process (process 1 or HARQ process 1) may be enabled and a second process (process 2 or HARQ process 2) may be disabled. Alternatively, the first process may be configured to enable HARQ feedback through RRC signaling, and the second process may be configured to disable HARQ feedback through RRC signaling. In this case, when the first process 1 is indicated by DCI, information related to a PUCCH may be indicated by a TPC command field for a scheduled PUCCH, a PUCCH resource indicator field, and a HARQ feedback timing indicator (or a PDSCH-to-HARQ_feedback timing indicator) field, included in the DCI.

In contrast, when the second process is indicated by the DCI (indicated as being disabled), the information related to the PUCCH is not indicated by the TPC command field for the scheduled PUCCH, the PUCCH resource indicator field, and the HARQ feedback timing indicator (or the PDSCH-to-HARQ_feedback timing indicator) field, included in the DCI. Instead, other (e.g., PDSCH repetition) information is indicated.

Specifically, in the case of the second process (or HARQ process 2), repetition of a PDSCH may be indicated, and the success rate of decoding the PDSCH may be increased through such repetition. In other words, when the second process is indicated by RRC, the UE may interpret information about repetition as being indicated through specific fields of the DCI (the TPC command field, the PUCCH resource indicator field, and/or the HARQ feedback timing indicator field).

Here, the information related to repetition (the number of repeated transmissions, a slot interval, and/or a repetition window size) may be predefined or configured (by the gNB). Alternatively, one of a plurality of predefined repetition patterns may be preconfigured as the information related to repetition or may be configured or indicated by the gNB. Alternatively, the slot interval may be configured as a specific value. For example, the slot interval may be configured based on or in correspondence to a PDSCH decoding/processing time of the UE. (the number of OFDM symbols required for UE processing from the end of PDSCH reception to the earliest possible start of corresponding HARQ-ACK transmission from the perspective of the UE).

On the other hand, since a disabled HARQ process ID may have no particular meaning, multi-transmission time interval (TTI) PDSCH (i.e., different TBs across multiple slots) scheduling information, other than PDSCH repetition (i.e., same TB across multiple slots), may be indicated by the TPC command for the scheduled PUCCH, the PUCCH resource indicator field, and/or the HARQ feedback timing indicator field. In other words, in the case of HARQ disabling, the following cases may further be considered in order to improve reliability.

-   -   Multi-slot level repetition: a plurality of multi-slot         repetitions may be scheduled for a single TB to improve the         reliability of a plurality of TB transmissions.     -   The UE may make a request (to the gNB) for a conservative MCS or         use a table for URLLC (e.g., Table 3 of TS 38.214) as a basic         MCS table.

(2) Second DCI Interpretation Method: Case in which HARQ-Enabled/Disabled is Indicated by DCI

The second DCI interpretation method relates to a method of interpreting the DCI when HARQ-enabled/disabled is dynamically indicated by the DCI even with respect to the same HARQ process ID. Here, whether HARQ is enabled/disabled may be indicated through the HARQ feedback timing indicator field of the DCI and/or the PUCCH resource indicator field of the DCI or may be indicated through a MAC-CE of a MAC layer.

For example, when a numerical value (e.g., K1 value) is indicated by the HARQ feedback timing indicator (or PDSCH-to-HARQ_feedback timing indicator) field, HARQ may be enabled. In other words, when the numerical value (e.g., K1 value) is indicated by the HARQ feedback timing indicator (or PDSCH-to-HARQ_feedback timing indicator) field of the DCI, the UE may interpret the DCI as indicating HARQ-enabled. In this case, since HARQ feedback operates, a PUCCH resource may be indicated by the TPC command for the scheduled PUCCH and/or the PUCCH resource indicator field. In other words, when the HARQ feedback timing indicator has the numerical value (when HARQ feedback-enabled is indicated), the UE may acquire or is configured with information about the PUCCH resource through the TPC command field for the scheduled PUCCH and/or the PUCCH resource indicator field, included in the DCI.

In contrast, when a non-numerical value is indicated for the K1 value by the HARQ feedback timing indicator field, the UE may recognize this value as HARQ-disabled. In this case, the UE may interpret or determine that other information (e.g., PDSCH repetition or multi-TTI PDSCH scheduling information) is indicated through the TPC command field for the scheduled PUCCH and/or the PUCCH resource indicator field. In other words, when the non-numerical value is indicated for the K1 value by the HARQ feedback timing indicator (or PDSCH-to-HARQ feedback timing indicator) field (when DCI indicates that HARQ is disabled), the UE may interpret the TPC command field for the scheduled PUCCH and/or the PUCCH resource indicator field, included in the DCI, as including or indicating other information (e.g., PDSCH repetition or multi-TTI PDS CH scheduling information).

Alternatively, if the PUCCH resource indicator field indicates a valid resource, the UE may recognize the resource as HARQ-enabled, and if the PUCCH resource indicator field indicates an invalid resource, the UE may recognize the resource as HARQ-disabled. In this case, PDSCH retransmission (or multi-TTI PDSCH) information is indicated by K1 and/or the TPC command for the scheduled PUCCH. In other words, when the PUCCH resource indicator included in the received DCI indicates the invalid resource, the UE may interpret K1 and/or the TPC command field for the scheduled PUCCH as including the PDSCH retransmission (or multi-TTI PDSCH) information.

Alternatively, HARQ feedback-enabled/disabled may be dynamically indicated through a MAC-CE and may be indicated for each HARQ process in the form of a bitmap. In other words, HARQ feedback-enabled/disabled may be dynamically indicated through the MAC-CE and may be indicated for each HARQ process by a bitmap included in the MAC-CE.

3. Proposal 3 (Report/Request of UE for HARQ Feedback-Enabled/Disabled)

(1) RSRP/CQI/SINR Reporting

A periodic/semi-periodic channel state information reference signal (CSI-RS) may be configured, and periodic/semi-periodic RSRP/CQI/SINR reporting by the UE may be performed. For example, in CSI reporting, the UE may be configured with CSI-RS resource indicator (cri) reference signal received power (cri-RSRP), cri signal-to-interference-plus-noise ratio (cri-SINR), and/or cri channel quality indicator (cri-CQI) among report quantities and may report CSI for cri-RSRP, cri-SINR, and/or cri-CQI.

In this case, a dedicated CSI-RS may be configured for the purpose of HARQ feedback-enabled/disabled, and CRI may be omitted.

(2) Request for MCS Change

For example, referring to Table 14, reporting may be performed using 2 bits as follows. In other words, a request for MCS change may be performed using 2 bits as shown in Table 13. Here, when the UE reports a request for MCS change that requests an increase in an MCS (e.g., state=00), the gNB may interpret or determine that the UE make a request to enable HARQ feedback. In contrast, when the UE reports a request for MCS change that requests the reduction of the MCS (e.g., state=10), the gNB may interpret or determine that the UE make a request to disable HARQ feedback.

TABLE 14 State Description 00 MCS increase 01 No change 10 MCS decrease 11 Reserved

(3) Request for Change in Number of PDSCH Repetitions and/or Pattern

Similar to the method of “(2) Request for MCS change”, when the UE reports a request for an increase in the number of PDSCH repetitions, the gNB may understand that the UE requests that HARQ feedback be enabled. In contrast, when the UE reports a request for a decrease in the number of PDSCH repetitions, the gNB may understand that the UE requests that HARQ feedback be disabled. In this case, the number of repetitions or a pattern serving as a criterion may be previously fixed to a specific value or may be configured by the gNB for the UE. In other words, the gNB may enable HARQ feedback for the UE when the UE reports a request for an increase in the number of PDSCH repetitions and may disable HARQ feedback for the UE when the UE reports a request for a decrease in the number of PDSCH repetitions.

4. Proposal 4 (Method of Configuring a Default HARQ Operating Mode of the UE)

Proposal 4 relates to a method of configuring a default HARQ operation mode for the UE before RRC connection/configuration (for a HARQ operation mode). The method of configuring the default HARQ operation mode for the UE may include the following first mode configuration method and second mode configuration method.

(1) First Mode Configuration Method

When a cell (accessed by the UE) is indicated as an NTN cell through a physical broadcast channel (PBCH) (master information block (MIB)) or an SIB, the UE assumes/recognizes a default mode as a HARQ-disabled configuration and operates. When the cell indicated by the UE is indicated as the NTN cell through the PBCH (MIB) or the SIB, this may be the case in which a specific TA offset (per beam), a specific PRACH sequence, and/or a specific timing offset (K_offset) (limited to be applied only to an NTN) is configured through the PBCH (MIB) or the SIB. In other words, the UE may configure HARQ-disabled as the default HARQ mode when a parameter related to the NTN cell (the specific TA offset, the specific PRACH sequence, and/or the specific timing offset related to the NTN cell) is included in the received PBCH (MIB) or the SIB.

As shown in Table 15 below (see TR 38.821), the specific timing offset may be a timing offset applied to (or independently/integrally applied to) at least one of a transmission timing for a PUSCH scheduled by DCI, a transmission timing for a PUSCH scheduled by an RAR grant, a transmission timing for HARQ-ACK on a PUCCH, a MAC CE action timing, CSI reference resource timing, and/or an aperiodic SRS transmission timing.

TABLE 15 6.2.1.1 Background The existing NR timing relationships are described as follows.  • PDSCH reception timing: When the UE is scheduled to receive  PDSCH by a DCI, the DCI indicates the slot offset K₀ among other   ${{{{things}.{The}}{slot}{allocated}{for}{the}{PDSCH}{is}\left\lfloor {n \cdot \frac{2^{\mu_{PDSCH}}}{2^{\mu_{PDCCH}}}} \right\rfloor} + K_{0}},$  where n is the slot with the scheduling DCI, K₀ is based on the  numerology of PDSCH, and μ_(PDSCH) and μ_(PDCCH) are the subcarrier  spacing configurations for PDSCH and PDCCH, respectively. The  value of K₀ is in the range of 0, ... , 32.  • Transmission timing for PUSCH scheduled by DCI: When the UE is  scheduled to transmit PUSCH by a DCI, the DCI indicates the slot  offset K₂ among other things. The slot allocated for the PUSCH is   ${\left\lfloor {n \cdot \frac{2^{\mu_{PUSCH}}}{2^{\mu_{PDCCH}}}} \right\rfloor + K_{2}},{{where}n{is}{the}{slot}{with}{the}{scheduling}{DCI}},$  K₂ is based on the numerology of PUSCH, and μ_(PUSCH) and μ_(PDCCH) are  the subcarrier spacing configurations for PUSCH and PDCCH,  respectively. The value of K₂ is in the range of 0, ... , 32.  • Transmission timing for PUSCH scheduled by RAR grant: With  reference to slots for a PUSCH transmission scheduled by a RAR UL  grant, if a UE receives a PDSCH with a RAR message ending in slot n  for a corresponding PRACH transmission from the UE, the UE  transmits the PUSCH in slot n + K₂ + Δ, where K₂ and Δ are provided  in TS 38.214.  • Transmission timing for HARQ-ACK on PUCCH: With reference to  slots for PUCCH transmissions, for a PDSCH reception ending in slot  n or a SPS PDSCH release through a PDCCH recepton ending in slot  n, the UE provides corresponding HARQ-ACK information in a  PUCCH transmission within slot n + K₁, where K₁ is a number of slots  and is indicated by the PDSCH-to-HARQ-timing-indicator field in the  DCI format, if present, or provided by dl-DataToUL-ACK. K₁ = 0  corresponds to the last slot of the PUCCH transmission that overlaps  with the PDSCH reception or with the PDCCH reception in case of  SPS PDSCH release.  • MAC CE action timing: When the HARQ-ACK corresponding to a  PDSCH carrying a MAC-CE command is transmitted in slot n, the  corresponding action and the UE assumption on the downlink  configuration indicated by the MAC-CE command shall be applied  starting from the first slot that is after slot n + 3N_(slot) ^(subframe,μ), where  N_(slot) ^(subframe,μ) denotes the number of slots per subframe for subcarrier  spacing configuration μ.  • Transmission timing for CSI on PUSCH: The transmission timing of  CSI on PUSCH follows the general transmission timing for DCI  scheduled PUSCH.  • CSI reference resource timing: The CSI reference resource for a CSI  report in uplink slot n′ is defined by a single downlink slot n − n_(CSI)_ref,   ${{{where}n} = {\left\lfloor {n^{\prime} \cdot \frac{2^{\mu_{DL}}}{2^{\mu_{UL}}}} \right\rfloor.{Here}}},{\mu_{DL}{and}\mu_{UL}{are}{the}{subcarrier}}$  spacing configurations for DL and UL, respectively. The value of  n_(CSI)_ref depends on the type of CSI report and is defined in TS 38.214.  • Aperiodic SRS transmission timing: If a UE receives a DCI triggering  aperiodic SRS in slot n, the UE transmits aperiodic SRS in each of the   ${{{triggered}{SRS}{resource}{{set}(s)}{in}{slot}\left\lfloor {n \cdot 2^{\frac{\mu_{SRS}}{\mu_{PDCCH}}}} \right\rfloor} + k},{where}$  k is configured via higher layer parameter slotOffset for each triggered  SRS resources set and is based on the subcarrier spacing of the  triggered SRS transmission, μ_(SRS) and μ_(PDCCH) are the subcarrier spacing  configurations for triggered SRS and PDCCH carrying the triggering  command respectively. The existing NR timing definitions involving DL-UL timing interaction may not hold when there is a large offset in the UE's DL and UL frame timing in NTN. Thus, the timing relationships need to be enhanced. 6.2.1.2 Enhancements The PDSCH reception timing is defined solely from DL timing perspective. It is not impacted by the large offset in the UE's DL and UL frame timing and thus enhancement is not needed. The other timing relationships described in Section 6.2.1.1involve DL-UL timing interaction and thus need to be enhanced for NTN. The enhancement can be to introduce an offset K_(offset) and applying it to modify the relevant timing relationships.  • For the transmission timing of DCI scheduled PUSCH (including CSI  on PUSCH), the slot allocated for the PUSCH can be modified to be   $\left\lfloor {n \cdot \frac{2^{\mu_{PUSCH}}}{2^{\mu_{PDCCH}}}} \right\rfloor + K_{2} + {K_{offset}.}$  • For the transmission timing of RAR grant scheduled PUSCH, the UE  transmits the PUSCH in slot n + K₂ + Δ + K_(offset).  • For the transmission timing of HARQ-ACK on PUCCH, the UE  provides corresponding HARQ-ACK information in a PUCCH  transmission within slot n + K₁ + K_(offset).  • For the MAC CE action timing, the corresponding action and the UE  assumption on the downlink configuration indicated by the MAC-CE  command shall be applied starting from the first slot that is after slot  n + XN_(slot) ^(subframe,μ) + K_(offset), where the value of X may depend on NTN  UE capability and may not necessarily be equal to 3. How to determine  the value of X is for further study.  • For the CSI reference resource timing, the CSI reference resource is  given in the downlink slot n − n_(CSI) _(ref) − K_(offset).  • For the transmission timing of aperiodic SRS, the UE transmits  aperiodic SRS in each of the triggered SRS resource set(s) in slot   $\left\lfloor {n \cdot 2^{\frac{\mu_{SRS}}{\mu_{PDCCH}}}} \right\rfloor + k + {K_{offset}.}$ The values of K_(offset) may be different for each of the identified timing relationships that need to be modified for NTN. The values of K_(offset) can be per beam or per-cell. It is for further study whether K_(offset) is derived from broadcast information or is signaled by higher layers. The possibility of extending the range K₁ and/or K₂ beyond what is supported in NR Rel-15 can be further discussed when the specifications are developed.

The case in which HARQ-disabled is configured as the default HARQ mode may mean that a HARQ feedback and/or HARQ retransmission operation is disabled as in the first case, the second case, and/or the third case in Proposal 1 mentioned above. For example, when HARQ-disabled is configured as the default HARQ mode, this may correspond to at least one of the case in which HARQ feedback is disabled and data retransmission is not supported (the first case), the case in which HARQ feedback is disabled and data retransmission is supported (the second case), or the case in which HARQ feedback is enabled and data transmission is not supported (the third case).

Alternatively, when HARQ-disabled is configured as the default HARQ mode, the UE may apply the DCI format configuration method of Proposal 1 described above for at least CSS DCI and/or a fallback DCI format (the above-described first case, second case, and/or third case). In other words, when HARQ-disabled is configured as the default HARQ mode, all or part of the fields related to HARQ may be omitted from the DCI as in the above-described first to third cases in Proposal 1.

(2) Second Mode Configuration Method

In the second mode configuration method, which one of a HARQ-disabled configuration and a HARQ-enabled configuration is configured as the default operation mode is indicated (when the NTN cell is indicated) through the PBCH (MIB) or the SIB. In other words, in the second mode configuration method, the HARQ default operation mode may be indicated by the PBCH (MIB) or SIB related to the NTN cell.

Here, the HARQ-disabled configuration(s) may be previously indicated or designated from among the above-described first, second, and third cases of Proposal 1. For example, any one of the case in which HARQ feedback is disabled and data retransmission is not supported (the first case), the case in which HARQ feedback is disabled and data retransmission is supported (the second case), and the case in which HARQ feedback is enabled and data transmission is not supported (the third case) may be indicated through the PBCH (MIB) or the SIB.

Alternatively, the HARQ-enabled configuration may mean the case in which both HARQ feedback and data retransmission are enabled.

Alternatively, if the default mode is indicated as HARQ-disabled through the PBCH (MIB) or the SIB, at least one of the first case, the second case, or the third case of Proposition 1 may be applied to at least one of the CSS DCI and/or the fallback DCI format. Alternatively, if the default mode is indicated as HARQ-enabled through the PBCH (MIB) or the SIB, an existing legacy DCI configuration may be applied.

5. Proposal 5 (HARQ-Enabled/Disabled is Indicated Based on SPS Configuration)

Proposal 5 may be a method of configuring HARQ-disabled using semi-persistent scheduling (SPS).

SPS has been introduced to remarkably reduce control channel overhead of an application requiring continuous radio resource allocation, such as voice over Internet protocol (VoIP). This is because, if there is no SPS, allocation of all DL and/or UL resources should be granted or allocated through an access grant message on a PDCCH.

When using SPS, activation/release may be configured by a combination of code points of specific fields in DCI as defined in Tables 16 and 17 (refer to TS 38.213). Here, the specific fields in the DCI may include a HARQ process number field, an RV field, an MCS field, and a frequency domain resource assignment field (refer to Table 16 and/or Table 17).

TABLE 16 DCI format DCI format DCI format 0_0/0_1/0_2 1_0/1_2 1_1 HARQ process set to all set to all ‘0’s set to all ‘0’s number ‘0’s/0_2 Redundancy set to all ‘0’s set to all ‘0’s For the enabled version transport block: set to all ‘0’s

TABLE 17 DCI format DCI format 0_0/0_1/0_2 1_0/1_1/1_2 HARQ process number set to all ‘0’s set to all ‘0’s Redundancy version set to all ‘0’s set to all ‘0’s Modulation and set to all ‘1’s set to all ‘1’s coding scheme Frequency domain set to all ‘0’s for FDRA set to all ‘0’s for resource assignment Type 0 or for FDRA Type FDRA Type 0 2 with μ = 1, set to all ‘1’s for set to all ‘1’s for FDRA FDRA Type 1 Type 1 or for FDRA Type 2 with μ = 0

Even in the above-described NTN, SPS may be applied or introduced for the purpose of greatly reducing control channel overhead. In other words, even in the case of DL SPS, HARQ feedback may be enabled or disabled according to quality of service (QoS) of a corresponding TB or a channel situation. Specific details are as follows.

(1) First Indication Method—Indication Through DCI

The first indication method may be a method of indicating HARQ feedback-enabled/disabled for a predetermined time through DCI in a situation in which an SPS PDSCH is activated and a PUCCH resource is given (or a situation in which a PUCCH resource is allocated).

Specifically, in a situation in which the SPS PDSCH is activated and the PUCCH resource is given (or a situation in which the PUCCH resource is allocated), HARQ feedback may be activated or deactivated for a predetermined time through separate DCI. For example, activation or deactivation of a specific HARQ process may be indicated or configured through DCI different from DCI for activating the SPS PDSCH. Here, the activated/deactivated HARQ process may be all or part of HARQ processes configured for the UE.

Alternatively, when activation/deactivation of the HARQ process is indicated through the DCI for activating the SPS PDSCH, a specific HARQ process enable field may be newly defined or configured in the DCI. In other words, the SPS PDSCH may be enabled through one DCI, and activation/deactivation of the HARQ process may be indicated through the specific HARQ process enable field newly defined in the one DCI.

(2) Second Indication Method—Indication Through an SPS Configuration (e.g., RRC Signaling)

The second indication method may be a method in which a plurality of SPSs is configured, and aHARQ feedback enabled SPS and aHARQ feedback disabled SPS are configured separately. In other words, the second indication method may be a method of receiving a plurality of SPS configurations including an SPS configuration in which HARQ feedback is enabled and an SPS configuration in which HARQ feedback is disabled.

For example, multiple SPS configurations may be distinguished by an index/ID (e.g., sps-Configlndex-r16), and a HARQ feedback enable/disable field is newly configured/set for each SPS configuration corresponding to each index/ID. In this case, an SPS configuration in which HARQ feedback is enabled or an SPS configuration in which HARQ feedback is disabled may be configured/indicated based on the newly configured field.

In the case of the second indication method, a separate HARQ enable field may be newly defined in and/or added to SPS-Config defined in Table 18 (see TS 38.331). When SPS is configured, HARQ feedback enabled SPS and HARQ feedback disabled SPS may be configured through the HARQ enable field. That is, in the case of the second indication method, HARQ feedback-enabled or HARQ feedback-disabled may be indicated with respect to each SPS configuration through SPS configuration information (or a separate field included in an SPS-Config parameter) received from higher layer signaling (e.g., RRC signaling) of the gNB (or NTN).

TABLE 18  SPS-Config  The IE SPS-Config is used to configure downlink semi-persistent transmission. Multiple Downlink SPS configurations  may be configured in one BWP of a serving cell.    SPS-Config information element  -- ASN1START  -- TAG-SPS-CONFIG-START  SPS-Config ::=  SEQUENCE {   periodicity   ENUMERATED {ms10, ms20, ms32, ms40, ms64, ms80, ms128, ms160,  ms320, ms640,     spare6, spare5, spare4, spare3, spare2,  spare1},   nrofHARQ-Processes   INTEGER {1..8},   n1PUCCH-AN   PUCCH-ResourceId  OPTIONAL, -- Need M   mcs-Table   ENUMERATED {qam64LowSE}  OPTIONAL, -- Need S   ...,   [[   sps-ConfigIndex-r16  SPS-ConfigIndex-r16  OPTIONAL, -- Need N   harq-ProcID-Offset-r16  INTEGER {0..15}  OPTIONAL, -- Need N   periodicityExt-r16  INTEGER {1..5120}  OPTIONAL, -- Need N   harq-CodebookID-r16  INTEGER {1..2}  OPTIONAL -- Need N   ]]  }  -- TAG-SPS-CONFIG-STOP  -- ASN1STOP     SPS-Config field descriptions harq-CodebookID Indicates the HARQ-ACK codebook index for the corresponding HARQ-ACK codebook for SPS PDSCH and ACK for SPS PDSCH release. harq-ProcID-Offset Indicates the offset used in deriving the HARQ process IDs, see TS 38.321 [3], clause 5.3.1. mcs-Table Indicates the MCS table the UE shall use for DL SPS (see TS 38.214 [19],clause 5.1.3.1. If present, the UE shall use the MCS table of low-SE 64QAM table indicated in Table 5.1.3.1-3 of TS 38.214 [19]. If this field is absent and field mcs-table in PDSCH-Config is set to ′qam256′ and the activating DCI is of format 1_1, the UE applies the 256QAM table indicated in Table 5 1.3.1-2 of TS: 38.214 [19]. Otherwise, the UE applies the non-low-SE 64QAM table indicated in Table 5.1.3.1-1 of TS 38.214 [19]. n1PUCCH-AN HARQ resource for PUCCH for DL SPS. The network configures the resource either as format0 or format1. The actual PUCCH-Resource is configured in PUCCH-Config and referred to by its ID. See TS 38.213 [13], clause 9.2.3. nrofHARQ-Processes Number of configured HARQ processes for SPS DL (see TS 38.321 [3], clause 5.8.1). periodicity Periodicity for DL SPS (see TS 38.214 [19] and TS 38.321 [3], clause 5.8.1). periodicityExt This field is used to calculate the periodicity for DL SPS (see TS 38.214 [19] and see TS 38.321 [3], clause 5,8.1). If this field is present, the field periodicity is ignored: The following periodicities are supported depending on the configured subcarrier spacing [slots]: 15 KHz: periodicityExt, where periodicityExt has a value between 1 and 640 30 KHz: periodicityExt, where periodicityExt has a value between 1 and 1280. 60 KHz with normal CP: periodicityExt, where periodicityExt has a value between 1 and 2560. 60 KHz with ECP: periodicityExt, where periodicityExt has a value between 1 and 2560. 120 KHz:    periodicityExt, where periodicityExt has a value between 1 and 5120. sps-ConfigIndex Indicates the index of one of multiple SPS configurations

Examples of the above-described proposed methods may also be included as one of implementation methods of the present disclosure and, therefore, it is obvious that the examples are regarded as the proposed methods. In addition, although the above-described proposed methods may be independently implemented, the proposed methods may be implemented in the form of a combination (or integration) of some of the proposed methods. A rule may be defined such that a BS informs a UE of information as to whether to apply the proposed methods (or information about rules of the proposed methods) through a predefined signal (e.g., a physical layer signal or a higher layer signal). A higher layer may include, for example, one or more of functional layers such as a media access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, an RRC layer, and a service data adaptation protocol (SDAP) layer.

The methods, embodiments, or descriptions for implementing the method proposed in this disclosure may be applied separately or in combination of one or more methods (or embodiments or descriptions).

FIG. 12 is a flowchart illustrating a method for a UE to perform a UL transmission operation based on the above-described embodiments, and FIG. 13 is a flowchart illustrating a method for a UE to perform a DL reception operation based on the above-described embodiments.

The UE may perform NR NTN or LTE NTN transmission and reception of one or more physical channels/signals based on at least one of Proposal 1, Proposal 2, Proposal 3, Proposal 4, or Proposal 5 described above. Meanwhile, at least one step illustrated in FIGS. 12 and 13 may be omitted according to situations or configurations, and steps illustrated in FIGS. 12 and 13 are described only for convenience of explanation and do not limit the scope of the present disclosure.

Referring to FIG. 12 , the UE may receive configuration information related to an NTN and information related to UL data/UL channels (M31). Next, the UE may receive DCI/control information for transmission of the UL data and/or UL channels (M33). The DCI/control information may include scheduling information for transmission of the UL data/UL channels. Next, the UE may transmit the UL data/UL channels based on the scheduling information (M35). The UE may transmit the UL data/UL channels until all configured/indicated UL data/UL channels are transmitted. When all the UL data/UL channels are transmitted, the corresponding UL transmission operation may be ended (M37).

Referring to FIG. 13 , the UE may receive configuration information related to an NTN and information related to DL data and/or DL channels (M41). Next, the UE may receive DCI/control information for reception of the DL data and/or the DL channels (M43). The DCI/control information may include scheduling information of the DL data/DL channels. The UE may receive the DL data/DL channels based on the scheduling information (M45). The UE may receive the DL data/DL channels until all configured/indicated DL data/DL channels are received, and when all DL data/DL channels are received, the UE may determine whether transmission of feedback information for the received DL data/DL channels is needed (M47 and M48). If it is necessary to transmit the feedback information, the UE may transmit HARQ-ACK feedback and, if not, the UE may end the reception operation without transmitting HARQ-ACK feedback (M49). Whether the feedback information needs to be transmitted and/or a field configuration included in the DCI may be configured based on Proposals 1 to 5 described above.

FIG. 14 is a flowchart illustrating a method for a BS to perform a UL reception operation based on the above-described embodiments, and FIG. 15 is a flowchart illustrating a method for a BS to perform a DL transmission operation based on the above-described embodiments.

The BS may perform NR NTN or LTE NTN transmission and reception of one or more physical channels/signals based on at least one of Proposal 1, Proposal 2, Proposal 3, Proposal 4, or Proposal 5 described above. Meanwhile, at least one step illustrated in FIGS. 14 and 15 may be omitted according to situations or configurations, and steps illustrated in FIGS. 14 and 15 are described only for convenience of explanation and do not limit the scope of the present disclosure.

Referring to FIG. 14 , the BS may transmit configuration information related to an NTN and information related to UL data/UL channels to the UE (M51). Next, the BS may transmit DCI/control information for transmission of the UL data and/or UL channels (to the UE) (M53). The DCI/control information may include scheduling information for transmission of the UL data/UL channels. Next, the BS may receive the UL data/UL channels (from the UE) based on the scheduling information (M55). The BS may receive the UL data/UL channels until all configured/indicated UL data/UL channels are received. When all the UL data/UL channels are received, the corresponding UL reception operation may be ended (M57).

Referring to FIG. 15 , the gNB may transmit configuration information related to an NTN and information related to DL data and/or DL channels (to the UE) (M61). Next, the BS may transmit DCI/control information for reception of the DL data and/or DL channels (M63). The DCI/control information may include scheduling information of the DL data/DL channels. The BS may transmit the DL data/DL channels (to the UE) based on the scheduling information (M65). The BS may transmit the DL data/DL channels until all configured/indicated DL data/DL channels are transmitted, and when all DL data/DL channels are transmitted, the BS may determine whether reception of feedback information for the DL data/DL channels is needed (M67 and M68). If it is necessary to receive the feedback information, the BS may receive HARQ-ACK feedback and, if not, the BS may end the DL transmission operation without receiving HARQ-ACK feedback (M69). Whether the feedback information needs to be received and/or a field configuration included in the DCI may be configured based on Proposals 1 to 5 described above.

FIGS. 16 and 17 are flowcharts illustrating methods of performing signaling between a BS and a UE based on the above-described embodiments.

The BS and the UE may perform NR NTN or LTE NTN transmission and reception of one or more physical channels/signals based on at least one of Proposal 1, Proposal 2, Proposal 3, Proposal 4, or Proposal 5 described above.

Referring to FIG. 16 , the UE and the BS may perform a UL data/channel transmission/reception operation and, referring to FIG. 17 , the UE and the BS may perform a DL data/channel transmission/reception operation.

Although not illustrated in FIGS. 16 and 17 , a default HARQ operation mode of the UE may be configured in a step before RRC connection/configuration as described above in proposed method (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, or Proposal 5). For example, when a cell (accessed by the UE) is indicated as an NTN cell through a PBCH (MIB) or an SIB, the UE may configure the default mode as HARQ-disabled. Alternatively, one of a HARQ-disabled configuration and a HARQ-enabled configuration may be indicated as the default HARQ operation mode through the PBCH (MIB) or the SIB (e.g., when the NTN cell is indicated).

Referring to FIG. 16 , the BS may transmit configuration information to the UE (M105). That is, the UE may receive the configuration information from the BS. For example, the configuration information may include configuration information related to an NTN, configuration information for UL transmission and reception (e.g., PUCCH-config and/or PUSCH-config), a HARQ process-related configuration (e.g., HARQ feedback-enabled/disabled and/or the number of HARQ processes), a CSI report-related configuration (e.g., CSI report configuration, CSI report quantity, and/or CSI-RS resource configuration), described in the above proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and/or Proposal 5). For example, the configuration information may be transmitted through higher layer (e.g., RRC or MAC CE) signaling. Alternatively, HARQ feedback-enabled/disabled may be configured for each cell group. Alternatively, HARQ feedback-enabled/disabled may be configured through information in the form of a bitmap. Alternatively, the configuration information may include an SPS-related configuration (e.g., SPS-config). Alternatively, the SPS-related configuration may include information about HARQ feedback-enabled/disabled.

Next, the BS may transmit the configuration information to the UE (M110). That is, the UE may receive the configuration information from the BS. For example, the configuration information may be transmitted/received through DCI. Alternatively, the configuration information may include control information for UL data/UL channel transmission and reception, scheduling information, resource allocation information, HARQ feedback-related information (e.g., an NDI, an RV, HARQ process number, a DL assignment index, a TPC command for a scheduled PUCCH resource indicator, and/or a PDSCH-to-HARQ_FEEDBACK timing indicator), a modulation and coding scheme (MCS), and frequency domain resource assignment. Here, the DCI may be one of DCI format 1_0 and DCI format 1_1. Alternatively, the HARQ feedback-related information may be included in fields of the DCI.

Alternatively, HARQ feedback-enabled/disabled may be configured based on the DCI as described in the above proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and/or Proposal 5). For example, HARQ feedback-enabled/disabled may be configured based on a PDSCH-to-HARQ_FEEDBACK timing indicator field and/or a PUCCH resource indicator field included in the DCI.

Alternatively, as described in the above proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and/or Proposal 5), when HARQ ACK feedback is disabled, some fields in the DCI may be omitted. For example, whether to configure a compact DCI format may be determined based on at least one of a DCI format or a type of a search space in which the DCI format is monitored (e.g., a CSS or a USS). Alternatively, a field constituting the DCI may be determined (e.g., which field is to be omitted may be determined) based on whether HARQ feedback is disabled/enabled and whether data retransmission is supported. For example, a field in the DCI associated with a disabled HARQ process may be used to indicate/configure other information (e.g., PDS CH repetition-related configuration/indication).

Alternatively, as described in Proposal 5 above, activation/deactivation of an SPS PDSCH may be indicated/configured based on the DCI. For example, HARQ feedback-enabled/disabled may be configured through separate DCI different from the DCI related to the activation/deactivation of the SPS PDSCH. Alternatively, the DCI related to the activation/deactivation of the SPS PDSCH may include a field related to HARQ feedback-enabled/disabled.

Next, the BS may receive UL data/UL channels (e.g., a PUCCH/PUSCH) from the UE (M115). That is, the UE may transmit the UL data/UL channels to the BS. For example, the UL data/UL channels may be received/transmitted based on the above-described configuration information. Alternatively, the UL data/UL channels may be received/transmitted based on the above-described proposed methods. Alternatively, CSI reporting may be performed through the UL data/UL channels. The CSI reporting may be performed based on information such as RSRP/CQI/SINR/CRI. Alternatively, the UL data/UL channels may include a request/report of the UE related to HARQ feedback-enabled/disabled. For example, as described in the above proposed methods, HARQ feedback-enabled/disabled may be reported/requested based on a report on increase/decrease of an MCS and/or a report on increase/decrease of the repetition of the PDSCH.

Referring to FIG. 17 , the BS may transmit configuration information to the UE (M205). That is, the UE may receive the configuration information from the BS. For example, the configuration information may include configuration information related to an NTN, configuration information for DL transmission and reception (e.g., PDCCH-config and/or PDSCH-config), a HARQ process-related configuration (e.g., HARQ feedback-enabled/disabled and/or the number of HARQ processes), a CSI report-related configuration (e.g., CSI report configuration, CSI report quantity, and/or CSI-RS resource configuration), described in the above proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and/or Proposal 5). For example, the configuration information may be transmitted through higher layer (e.g., RRC or MAC CE) signaling. Alternatively, HARQ feedback-enabled/disabled may be configured for each cell group. Alternatively, HARQ feedback-enabled/disabled may be configured through information in the form of a bitmap. Alternatively, the configuration information may include an SPS-related configuration (e.g., SPS-config). Alternatively, the SPS-related configuration may include information about HARQ feedback-enabled/disabled.

Next, the BS may transmit the configuration information to the UE (M210). That is, the UE may receive the configuration information from the BS. The configuration information may be transmitted/received through DCI. Alternatively, the configuration information may include control information for DL data/DL channel transmission and reception, scheduling information, resource allocation information, HARQ feedback-related information (e.g., an NDI, an RV, HARQ process number, a DL assignment index, a TPC command for a scheduled PUCCH resource indicator, and/or a PDSCH-to-HARQ_FEEDBACK timing indicator), an MCS, and frequency domain resource assignment. The DCI may be one of DCI format 1_0 and DCI format 1_1.

Alternatively, HARQ feedback-enabled/disabled may be configured based on the DCI as described in the above proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and/or Proposal 5). Alternatively, HARQ feedback-enabled/disabled may be configured based on a PDSCH-to-HARQ_FEEDBACK timing indicator field and/or a PUCCH resource indicator field included in the DCI.

Alternatively, when HARQ ACK feedback is disabled, some fields in the DCI may be omitted to configure a compact DCI format based on the above-described proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and/or Proposal 5). Alternatively, whether to configure the compact DCI format may be determined based on at least one of a DCI format or a type of a search space in which the DCI format is monitored (e.g., a CSS or a USS). Alternatively, a field constituting the DCI may be determined (e.g., which field is to be omitted may be determined) based on whether HARQ feedback is disabled/enabled and whether data retransmission is supported. Alternatively, a field in the DCI associated with a disabled HARQ process may be used to indicate/configure other information (e.g., PDSCH repetition-related configuration/indication).

Alternatively, as described in Proposal 5 above, activation/deactivation of an SPS PDSCH may be indicated/configured based on the DCI. For example, HARQ feedback-enabled/disabled may be configured through separate DCI different from the DCI related to the activation/deactivation of the SPS PDSCH. Alternatively, the DCI related to the activation/deactivation of the SPS PDSCH may include a field related to HARQ feedback-enabled/disabled.

Next, the BS may transmit DL data/DL channels (or a PDSCH) to the UE (M215). That is, the UE may receive the DL data/DL channels from the BS. The DL data/DL channels may be transmitted/received based on the above-described configuration information. Alternatively, the DL data/DL channels may be transmitted/received based on the above-described proposed methods.

Next, the BS may receive HARQ-ACK feedback from the UE (M220). That is, the UE may transmit HARQ-ACK feedback to the BS. HARQ-ACK feedback may be enabled/disabled based on the above-described proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and/or Proposal 5). Alternatively, when HARQ-ACK feedback is enabled, HARQ-ACK feedback may be transmitted and received based on the above-described proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and/or Proposal 5). Alternatively, HARQ-ACK feedback may include ACK/NACK information about the DL channels/DL data transmitted from the BS. For example, HARQ-ACK feedback may be transmitted through a PUCCH and/or a PUSCH.

The BS may generically refer to an object that performs transmission and reception of data with the UE. For example, the BS may be a concept including one or more transmission points (TPs) or one or more transmission and reception points (TRPs). In addition, the TP and/or the TRP may include a panel or a transmission/reception unit of the BS. In addition, “TRP” may be replaced with expressions such as panel, antenna array, cell (e.g., macro cell/small cell/pico cell), TP, and BS (gNB). As described above, the TRP may be distinguished according to information (e.g., an index or ID) about a CORESET group (or CORESET pool). As an example, when one UE is configured to perform transmission/reception with a plurality of TRPs (or cells), this may mean that a plurality of CORESET groups (or CORESET pools) is configured for one UE. Such a configuration for the CORESET group (or CORESET pool) may be performed through higher layer signaling (e.g., RRC signaling).

FIG. 18 is a diagram illustrating a method for a UE to receive a PDSCH from an NTN.

Referring to FIG. 18 , the UE may receive SPS configuration information from the NTN or the BS (TN) (S201).

The SPS configuration information may be transmitted to the UE through RRC signaling from the NTN or the BS. The SPS configuration information may include parameters defined in Table 18. Furthermore, the SPS configuration information may include information about a plurality of SPS configurations. The SPS configurations may include a first SPS configuration (or a first SPS configuration group) in which HARQ feedback for at least one HARQ process is configured to be enabled, and a second configuration (or a second SPS configuration group) in which HARQ feedback for at least one HARQ process is configured to be disabled.

The UE may configure an SPS configuration corresponding thereto among the plurality of SPS configurations based on an SPS index indicated by the SPS configuration information. In other words, the UE may receive a PDSCH or transmit a PUCCH and/or a PUSCH based on the SPS configuration corresponding to the SPS index included in the SPS configuration information.

Alternatively, the UE may determine whether to perform HARQ feedback for a HARQ process based on the SPS index indicated by the SPS configuration information. When the SPS index indicates the first SPS configuration among the SPS configurations, the UE may determine that HARQ feedback-enabled is indicated for a HARQ process for reception of the PDSCH based on the first SPS configuration. Alternatively, when the SPS index indicates the second SPS configuration among the SPS configurations, the UE may determine that HARQ feedback-disabled is indicated for the HARQ process for reception of the PDSCH based on the second SPS configuration.

Next, the UE may receive first DCI indicating whether an SPS configuration configured through the SPS configuration information is activated (S203). In other words, the UE may activate the SPS configuration for the PDSCH through the SPS configuration information based on the received DCI.

The first DCI may indicate whether the SPS configuration configured for the UE is activated through a combination of bits (or a combination of code points) included in at least two fields among the RV field, the HARQ process number field, the MCS field, and the frequency resource assignment field (refer to Tables 16 and 17). When the SPS configuration configured by the first DCI is activated, the UE may receive the PDSCH based on the SPS configuration.

Alternatively, the UE may receive, from the NTN, second DCI indicating or changing HARQ process-enabled/disabled for the activated SPS configuration separately from the first DCI. In this case, the UE may change a HARQ feedback-enabled/disabled configuration for at least one HARQ process for the SPS configuration according to the SPS configuration information based on the second DCI.

Next, the UE may receive the PDSCH from the NTN based on the activated SPS configuration (S205). The UE may periodically receive the PDSCH without a PDCCH based on the SPS configuration (refer to FIG. 7 ). In addition, the UE may transmit the PUCCH and/or the PUSCH on a preconfigured PUCCH and/or PUSCH resource without a grant based on the SPS configuration.

Next, the UE may determine whether to perform HARQ feedback for a HARQ process for the received PDSCH (or PDSCHs) based on the SPS configuration (S207).

Specifically, as described above, the SPS configuration configured for or indicated to the UE in the SPS configuration information may be the first SPS configuration or the second SPS configuration. When the first SPS configuration is configured by the SPS configuration information (i.e., the SPS configuration in which HARQ feedback for the HARQ process is configured to be enabled), the UE may transmit ACK/NACK information for the received PDSCH through the PUCCH or the PUSCH allocated based on the SPS configuration. In contrast, when the second SPS configuration is configured by the SPS configuration information (i.e., the SPS configuration in which the HARQ feedback for the HARQ process is configured to be disabled), the UE may not transmit the ACK/NACK information for the received PDSCH.

Alternatively, when the received second DCI indicates that the HARQ process for the SPS configuration is disabled, the UE may not transmit feedback information for the received PDSCH even if the first SPS configuration is configured as the SPS configuration. That is, upon receiving the second DCI, the UE may change HARQ feedback-enabled/disabled for the HARQ process for the SPS configuration through the second DCI.

FIG. 19 is a diagram illustrating a method for an NTN to transmit a PDSCH to a UE.

Referring to FIG. 19 , the NTN may transmit SPS configuration information including information about a plurality of SPS configurations to the UE (S301). Here, the NTN may be any one of a GEO satellite, an MEO satellite, an HEO satellite, an HAPS, or an LEO satellite.

The SPS configuration information may be transmitted to the UE through RRC signaling of the NTN. The SPS configuration information may include the parameters defined in Table 18. Furthermore, the SPS configuration information may include information about a plurality of SPS configurations. The SPS configurations may include a first SPS configuration (or a first SPS configuration group) in which HARQ feedback is configured to be enabled, and a second configuration (or a second SPS configuration group) in which HARQ feedback is configured to be disabled. The SPS configuration information may further include an SPS index indicating an SPS configuration configured for the UE. The NTN may transmit a PDSCH or receive a PUCCH and/or a PUSCH based on the SPS configuration corresponding to the SPS index included in the SPS configuration information.

Alternatively, the NTN may configure the SPS configuration for the UE through the SPS configuration information. The NTN may transmit, to the UE, the SPS configuration information including information about the SPS index for the SPS configuration corresponding to the UE, thereby configuring the SPS configuration corresponding to the UE. For example, the NTN may configure or indicate, through the SPS index as the SPS configuration corresponding to the UE, a first SPS configuration in which HARQ feedback for at least one HARQ process (or HARQ feedback) is enabled or a second SPS configuration in which HARQ feedback for at least one HARQ process (or HARQ feedback) is disabled.

Alternatively, the NTN may determine whether HARQ feedback for the at least one HARQ process for the SPS configuration is enabled or disabled (or which configuration of the first SPS configuration or the second SPS configuration is configured for the UE) based on channel information about a PDSCH and QoS of a TB related to the PDSCH. That is, the NTN may determine whether HARQ feedback for the HARQ process for the UE is enabled or disabled based on the channel information about the PDSCH related to the UE and the QoS of the TB and indicate or configure any one of the first SPS configuration and the second SPS configuration to or for the UE based on whether feedback for the HARQ process is enabled or disabled. In other words, the NTN may determine whether HARQ feedback for the HARQ process for the UE is enabled or disabled based on the channel information about the PDSCH related to the UE and the QoS of the TB and indicate a corresponding SPS configuration according to HARQ feedback-enabled/disabled. That is, the NTN may indicate and/or configure both the SPS configuration and HARQ feedback-enabled/disabled for the HARQ process for the SPS configuration to and for the UE through the SPS configuration information.

Next, the NTN may transmit first DCI indicating whether the SPS configuration configured through the SPS configuration information is activated (S303). That is, the NTN may activate the SPS configuration for the PDSCH based on the first DCI.

The first DCI may indicate whether the SPS configuration configured for the UE is activated through a combination of bits (or a combination of code points) included in at least two fields among the RV field, the HARQ process number field, the MCS field, and the frequency resource assignment field (refer to Tables 16 and 17). When the SPS configuration configured by the first DCI is activated, the NTN may transmit the PDSCH based on the SPS configuration.

Alternatively, the NTN may transmit, to the UE, second DCI indicating or changing HARQ process-enabled/disabled for the activated SPS configuration separately from the first DCI. In this case, the NTN may change HARQ feedback-enabled/disabled for the HARQ process configured for the UE according to the SPS configuration information through the second DCI.

Next, the NTN may transmit the PDSCH to the UE based on the activated SPS configuration (S305). The NTN may periodically transmit the PDSCH based on the SPS configuration and may not require transmission of a PDCCH (refer to FIG. 7 ). In addition, the NTN may receive the PUCCH and/or the PUSCH on a preconfigured PUCCH and/or PUSCH resource without a grant based on the SPS configuration.

Next, the NTN may determine whether to receive feedback information for the received PDSCH (or PDSCHs) based on the SPS configuration (S307). In other words, the NTN may determine whether to require reception of the feedback information for the received PDSCH (or PDSCHs) based on the SPS configuration.

Specifically, as described above, the NTN may configure the first SPS configuration or the second SPS configuration for the UE through the SPS configuration information. The NTN may configure HARQ feedback for the HARQ process for the UE to be enabled by configuring or indicating the first SPS configuration for or to the UE and configure HARQ feedback for the HARQ process for the UE to be disabled by configuring or indicating the second SPS configuration for or to the UE.

When the first SPS configuration is configured for the UE by the SPS configuration information (i.e., the SPS configuration in which HARQ feedback for the HARQ process is configured to be enabled), the NTN may receive ACK/NACK information for the PDSCH through the PUCCH or the PUSCH allocated based on the SPS configuration. In contrast, when the second SPS configuration is configured for the UE by the SPS configuration information (i.e., the SPS configuration in which the HARQ feedback for the HARQ process is configured to be disabled), the NTN may determine that reception of the ACK/NACK information for the received PDSCH is not needed.

Communication System Example to which the Present Disclosure is Applied

Although not limited thereto, various descriptions, functions, procedures, proposals, methods, and/or operational flow charts of the present disclosure disclosed in this document may be applied to various fields requiring wireless communication/connection (5G) between devices.

Hereinafter, it will be illustrated in more detail with reference to the drawings. In the following drawings/description, the same reference numerals may exemplify the same or corresponding hardware blocks, software blocks, or functional blocks, unless otherwise indicated.

FIG. 20 illustrates a communication system applied to the present disclosure.

Referring to FIG. 20 , a communication system 1 applied to the present disclosure includes wireless devices, Base Stations (BSs), and a network. Herein, the wireless devices represent devices performing communication using Radio Access Technology (RAT) (e.g., 5G New RAT (NR)) or Long-Term Evolution (LTE)) and may be referred to as communication/radio/5G devices. The wireless devices may include, without being limited to, a robot 100 a, vehicles 100 b-1 and 100 b-2, an eXtended Reality (XR) device 100 c, a hand-held device 100 d, a home appliance 100 e, an Internet of Things (IoT) device 100 f, and an Artificial Intelligence (AI) device/server 400. For example, the vehicles may include a vehicle having a wireless communication function, an autonomous driving vehicle, and a vehicle capable of performing communication between vehicles. Herein, the vehicles may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may include an Augmented Reality (AR)/Virtual Reality (VR)/Mixed Reality (MR) device and may be implemented in the form of a Head-Mounted Device (HMD), a Head-Up Display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). The home appliance may include a TV, a refrigerator, and a washing machine. The IoT device may include a sensor and a smartmeter. For example, the BSs and the network may be implemented as wireless devices and a specific wireless device 200 a may operate as a BS/network node with respect to other wireless devices.

The wireless devices 100 a to 100 f may be connected to the network 300 via the BSs 200. An AI technology may be applied to the wireless devices 100 a to 100 f and the wireless devices 100 a to 100 f may be connected to the AI server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. Although the wireless devices 100 a to 100 f may communicate with each other through the BSs 200/network 300, the wireless devices 100 a to 100 f may perform direct communication (e.g., sidelink communication) with each other without passing through the BSs/network. For example, the vehicles 100 b-1 and 100 b-2 may perform direct communication (e.g. Vehicle-to-Vehicle (V2V)/Vehicle-to-everything (V2X) communication). The IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100 a to 100 f.

Wireless communication/connections 150 a, 150 b, or 150 c may be established between the wireless devices 100 a to 100 f/BS 200, or BS 200/BS 200. Herein, the wireless communication/connections may be established through various RATs (e.g., 5G NR) such as uplink/downlink communication 150 a, sidelink communication 150 b (or, D2D communication), or inter BS communication (e.g. relay, Integrated Access Backhaul (IAB)). The wireless devices and the BSs/the wireless devices may transmit/receive radio signals to/from each other through the wireless communication/connections 150 a and 150 b. For example, the wireless communication/connections 150 a and 150 b may transmit/receive signals through various physical channels. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, and resource mapping/demapping), and resource allocating processes, for transmitting/receiving radio signals, may be performed based on the various proposals of the present disclosure.

Examples of Wireless Devices to which the Present Disclosure is Applied

FIG. 21 illustrates a wireless device applicable to the present disclosure.

Referring to FIG. 21 , a first wireless device 100 and a second wireless device 200 may transmit radio signals through a variety of RATs (e.g., LTE and NR). Herein, {the first wireless device 100 and the second wireless device 200} may correspond to {the wireless device 100 x and the BS 200} and/or {the wireless device 100 x and the wireless device 100 x} of FIG. 20 .

The first wireless device 100 may include one or more processors 102 and one or more memories 104 and additionally further include one or more transceivers 106 and/or one or more antennas 108. The processor(s) 102 may control the memory(s) 104 and/or the transceiver(s) 106 and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. For example, the processor(s) 102 may process information within the memory(s) 104 to generate first information/signals and then transmit radio signals including the first information/signals through the transceiver(s) 106. The processor(s) 102 may receive radio signals including second information/signals through the transceiver 106 and then store information acquired by processing the second information/signals in the memory(s) 104. The memory(s) 104 may be connected to the processor(s) 102 and may store a variety of information related to operations of the processor(s) 102. For example, the memory(s) 104 may store software code including commands for performing a part or the entirety of processes controlled by the processor(s) 102 or for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. Herein, the processor(s) 102 and the memory(s) 104 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver(s) 106 may be connected to the processor(s) 102 and transmit and/or receive radio signals through one or more antennas 108. Each of the transceiver(s) 106 may include a transmitter and/or a receiver. The transceiver(s) 106 may be interchangeably used with Radio Frequency (RF) unit(s). In the present disclosure, the wireless device may represent a communication modem/circuit/chip.

According to an embodiment, the first wireless device 100 or a UE may include the processor(s) 102 and the memory(s) 104, connected to the RF transceiver(s). The memory(s) 104 may include at least one program capable of performing operations related to the embodiments described with reference to FIGS. 10 to 19 .

Specifically, the processor(s) 102 may receive SPS configuration information through the RF transceiver(s) 106, receive first DCI that activates an SPS configuration related to the SPS configuration information, receive a PDSCH based on the SPS configuration, and determine whether to perform HARQ feedback for a HARQ process for the PDSCH based on the SPS configuration.

Alternatively, a chipset including the processor(s) 102 and the memory(s) 104 may be configured. In this case, the chipset may include at least one processor, and at least one memory operably connected to the at least one processor and causing, when executed, the at least one processor to perform operations. The operations may include receiving SPS configuration information, receiving first DCI that activates an SPS configuration related to the SPS configuration information, receiving a PDSCH based on the SPS configuration, and determining whether to perform HARQ feedback of a HARQ process for the PDSCH based on the SPS configuration. The at least one processor may perform operations for the embodiments described with reference to FIGS. 10 to 19 based on a program included in the memory(s).

Alternatively, a computer readable storage medium including at least one computer program that causes at least one processor to perform operations is provided. The operations may include receiving SPS configuration information, receiving first DCI that activates an SPS configuration related to the SPS configuration information, receiving a PDSCH based on the SPS configuration, and determining whether to perform HARQ feedback of a HARQ process for the PDSCH based on the SPS configuration. The computer program may include programs through which operations for the embodiments described with reference to FIGS. 10 to 19 may be performed.

The second wireless device 200 may include one or more processors 202 and one or more memories 204 and additionally further include one or more transceivers 206 and/or one or more antennas 208. The processor(s) 202 may control the memory(s) 204 and/or the transceiver(s) 206 and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. For example, the processor(s) 202 may process information within the memory(s) 204 to generate third information/signals and then transmit radio signals including the third information/signals through the transceiver(s) 206. The processor(s) 202 may receive radio signals including fourth information/signals through the transceiver(s) 106 and then store information acquired by processing the fourth information/signals in the memory(s) 204. The memory(s) 204 may be connected to the processor(s) 202 and may store a variety of information related to operations of the processor(s) 202. For example, the memory(s) 204 may store software code including commands for performing a part or the entirety of processes controlled by the processor(s) 202 or for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. Herein, the processor(s) 202 and the memory(s) 204 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver(s) 206 may be connected to the processor(s) 202 and transmit and/or receive radio signals through one or more antennas 208. Each of the transceiver(s) 206 may include a transmitter and/or a receiver. The transceiver(s) 206 may be interchangeably used with RF unit(s). In the present disclosure, the wireless device may represent a communication modem/circuit/chip.

According to an embodiment, a BS or an NTN may include the processor(s) 202 and/or the transceiver(s) 206. The processor(s) may transmit SPS configuration information, transmit first DCI that activates an SPS configuration related to the SPS configuration information, and transmit the PDSCH based on the SPS configuration, by controlling the transceiver(s) 106 or an RF transceiver, and determine whether to receive feedback information for a HARQ for the PDSCH based on the SPS configuration. The processor(s) 202 may perform operations based on the memory(s) 204 including at least one program capable of performing the operations related to the embodiments described with reference to FIGS. 10 to 19 .

Hereinafter, hardware elements of the wireless devices 100 and 200 will be described more specifically. One or more protocol layers may be implemented by, without being limited to, one or more processors 102 and 202. For example, the one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, and SDAP). The one or more processors 102 and 202 may generate one or more Protocol Data Units (PDUs) and/or one or more Service Data Unit (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. The one or more processors 102 and 202 may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. The one or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document and provide the generated signals to the one or more transceivers 106 and 206. The one or more processors 102 and 202 may receive the signals (e.g., baseband signals) from the one or more transceivers 106 and 206 and acquire the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document.

The one or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. The one or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. As an example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in the one or more processors 102 and 202. The descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be implemented using firmware or software and the firmware or software may be configured to include the modules, procedures, or functions. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be included in the one or more processors 102 and 202 or stored in the one or more memories 104 and 204 so as to be driven by the one or more processors 102 and 202. The descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be implemented using firmware or software in the form of code, commands, and/or a set of commands.

The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, code, instructions, and/or commands. The one or more memories 104 and 204 may be configured by Read-Only Memories (ROMs), Random Access Memories (RAMs), Electrically Erasable Programmable Read-Only Memories (EPROMs), flash memories, hard drives, registers, cash memories, computer-readable storage media, and/or combinations thereof. The one or more memories 104 and 204 may be located at the interior and/or exterior of the one or more processors 102 and 202. The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 through various technologies such as wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, control information, and/or radio signals/channels, mentioned in the methods and/or operational flowcharts of this document, to one or more other devices. The one or more transceivers 106 and 206 may receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document, from one or more other devices. For example, the one or more transceivers 106 and 206 may be connected to the one or more processors 102 and 202 and transmit and receive radio signals. For example, the one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may transmit user data, control information, or radio signals to one or more other devices. The one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may receive user data, control information, or radio signals from one or more other devices. The one or more transceivers 106 and 206 may be connected to the one or more antennas 108 and 208 and the one or more transceivers 106 and 206 may be configured to transmit and receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document, through the one or more antennas 108 and 208. In this document, the one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports). The one or more transceivers 106 and 206 may convert received radio signals/channels etc. from RF band signals into baseband signals in order to process received user data, control information, radio signals/channels, etc. using the one or more processors 102 and 202. The one or more transceivers 106 and 206 may convert the user data, control information, radio signals/channels, etc. processed using the one or more processors 102 and 202 from the base band signals into the RF band signals. To this end, the one or more transceivers 106 and 206 may include (analog) oscillators and/or filters.

Examples of Application of Wireless Devices to which the Present Disclosure is Applied

FIG. 22 illustrates another example of a wireless device applied to the present disclosure.

Referring to FIG. 22 , wireless devices 100 and 200 may correspond to the wireless devices 100 and 200 of FIG. 21 and may be configured by various elements, components, units/portions, and/or modules. For example, each of the wireless devices 100 and 200 may include a communication unit 110, a control unit 120, a memory unit 130, and additional components 140. The communication unit may include a communication circuit 112 and transceiver(s) 114. For example, the communication circuit 112 may include the one or more processors 102 and 202 and/or the one or more memories 104 and 204 of FIG. 21 . For example, the transceiver(s) 114 may include the one or more transceivers 106 and 206 and/or the one or more antennas 108 and 208 of FIG. 21 . The control unit 120 is electrically connected to the communication unit 110, the memory 130, and the additional components 140 and controls overall operation of the wireless devices. For example, the control unit 120 may control an electric/mechanical operation of the wireless device based on programs/code/commands/information stored in the memory unit 130. The control unit 120 may transmit the information stored in the memory unit 130 to the exterior (e.g., other communication devices) via the communication unit 110 through a wireless/wired interface or store, in the memory unit 130, information received through the wireless/wired interface from the exterior (e.g., other communication devices) via the communication unit 110.

The additional components 140 may be variously configured according to types of wireless devices. For example, the additional components 140 may include at least one of a power unit/battery, input/output (I/O) unit, a driving unit, and a computing unit. The wireless device may be implemented in the form of, without being limited to, the robot (100 a of FIG. 20 ), the vehicles (100 b-1 and 100 b-2 of FIG. 20 ), the XR device (100 c of FIG. 20 ), the hand-held device (100 d of FIG. 20 ), the home appliance (100 e of FIG. 20 ), the IoT device (100 f of FIG. 20 ), a digital broadcast terminal, a hologram device, a public safety device, an MTC device, a medicine device, a fintech device (or a finance device), a security device, a climate/environment device, the AI server/device (400 of FIG. 20 ), the BSs (200 of FIG. 20 ), a network node, etc. The wireless device may be used in a mobile or fixed place according to a use-example/service.

In FIG. 22 , the entirety of the various elements, components, units/portions, and/or modules in the wireless devices 100 and 200 may be connected to each other through a wired interface or at least a part thereof may be wirelessly connected through the communication unit 110. For example, in each of the wireless devices 100 and 200, the control unit 120 and the communication unit 110 may be connected by wire and the control unit 120 and first units (e.g., 130 and 140) may be wirelessly connected through the communication unit 110. Each element, component, unit/portion, and/or module within the wireless devices 100 and 200 may further include one or more elements. For example, the control unit 120 may be configured by a set of one or more processors. As an example, the control unit 120 may be configured by a set of a communication control processor, an application processor, an Electronic Control Unit (ECU), a graphical processing unit, and a memory control processor. As another example, the memory 130 may be configured by a Random Access Memory (RAM), a Dynamic RAM (DRAM), a Read Only Memory (ROM)), a flash memory, a volatile memory, a non-volatile memory, and/or a combination thereof.

Here, wireless communication technologies implemented in the wireless devices (XXX, YYY) of the present specification may include LTE, NR, and 6G, as well as Narrowband Internet of Things for low power communication. At this time, for example, the NB-IoT technology may be an example of a Low Power Wide Area Network (LPWAN) technology, and may be implemented in standards such as LTE Cat NB1 and/or LTE Cat NB2, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless devices (XXX, YYY) of the present specification may perform communication based on LTE-M technology. In this case, as an example, the LTE-M technology may be an example of LPWAN technology, and may be referred to by various names such as eMTC (enhanced machine type communication). For example, LTE-M technology may be implemented in at least one of a variety of standards, such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and/or 7) LTE M, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless devices (XXX, YYY) of the present specification is at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) considering low power communication, and is not limited to the above-described names. As an example, ZigBee technology can generate personal area networks (PANs) related to small/low-power digital communication based on various standards such as IEEE 802.15.4, and may be called various names.

The embodiments described above are those in which components and features of the present disclosure are combined in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, it is also possible to constitute an embodiment of the present disclosure by combining some components and/or features. The order of operations described in the embodiments of the present disclosure may be changed. Some configurations or features of one embodiment may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is obvious that the embodiments may be configured by combining claims that do not have an explicit citation relationship in the claims or may be included as new claims by amendment after filing.

In this document, embodiments of the present disclosure have been mainly described based on a signal transmission/reception relationship between a terminal and a base station. Such a transmission/reception relationship is extended in the same/similar manner to signal transmission/reception between a terminal and a relay or a base station and a relay. A specific operation described as being performed by a base station in this document may be performed by its upper node in some cases. That is, it is obvious that various operations performed for communication with a terminal in a network comprising a plurality of network nodes including a base station may be performed by the base station or network nodes other than the base station. The base station may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. In addition, the terminal may be replaced with terms such as User Equipment (UE), Mobile Station (MS), Mobile Subscriber Station (MSS).

In a hardware configuration, the embodiments of the present disclosure may be achieved by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

In a firmware or software configuration, a method according to embodiments of the present disclosure may be implemented in the form of a module, a procedure, a function, etc. Software code may be stored in a memory unit and executed by a processor. The memory unit is located at the interior or exterior of the processor and may transmit and receive data to and from the processor via various known means

As described before, a detailed description has been given of preferred embodiments of the present disclosure so that those skilled in the art may implement and perform the present disclosure. While reference has been made above to the preferred embodiments of the present disclosure, those skilled in the art will understand that various modifications and alterations may be made to the present disclosure within the scope of the present disclosure.

INDUSTRIAL APPLICABILITY

The above-described embodiments of the present disclosure are applicable to various mobile communication systems. 

What is claimed is:
 1. A method of receiving a physical downlink shared channel (PDSCH) by a user equipment (UE) from a non-terrestrial network (NTN) in a wireless communication system, the method comprising: receiving semi-persistent scheduling (SPS) configuration information; receiving first downlink control information (DCI) that activates an SPS configuration related to the SPS configuration information, wherein the SPS configuration is activated based on a value of a hybrid automatic repeat and request (HARQ) process number field and a value of a redundancy version (RV) field included in the DCI; receiving the PDSCH based on the SPS configuration; and wherein the SRS configuration information includes information on first indexes for a first SRS configuration in which the HARQ process is enabled and second indexes for a second SRS configuration in which the HARQ process is disabled.
 2. The method of claim 1, wherein the UE transmits acknowledgement/negative acknowledgement (ACK/NACK) for the PDSCH based on the SPS configuration for one of the first indexes. 3-4. (canceled)
 5. The method of claim 1, wherein the UE does not transmit acknowledgement/negative acknowledgement (ACK/NACK) for the PDSCH based on the SPS configuration for one of the second indexes.
 6. (canceled)
 7. The method of claim 1, wherein deactivation of the SPS configuration is determined based on a combination of bits included in at least two fields among the RV field, the HARQ process number, the modulation and coding scheme (MCS) field, and the frequency resource assignment field, included in the first DCI.
 8. The method of claim 1, wherein the NTN is related to at least one of a geostationary orbit (GEO) satellite, a medium-earth orbit (MEO) satellite, a high elliptical orbit (HEO) satellite, a high altitude platform station (HAPS), or a low earth orbit (LEO) satellite.
 9. A method of transmitting a physical downlink shared channel (PDSCH) by a non-terrestrial network (NTN) in a wireless communication system, the method comprising: transmitting semi-persistent scheduling (SPS) configuration information; transmitting first downlink control information (DCI) that activates an SPS configuration related to the SPS configuration information, wherein the SPS configuration is activated based on a value of a hybrid automatic repeat and request (HARQ) process number field and a value of a redundancy version (RV) field included in the DCI; transmitting the PDSCH based on the SPS configuration; and wherein the SRS configuration information includes information on first indexes for a first SRS configuration in which the HARQ process is enabled and second indexes for a second SRS configuration in which the HARQ process is disabled.
 10. (canceled)
 11. The method of claim 9, wherein the NTN determines whether HARQ feedback of at least one HARQ process for the SPS configuration is enabled or disabled based on channel information for the PDSCH and quality of service (QoS) of a transport block related to the PDSCH.
 12. A user equipment (UE) for receiving a physical downlink shared channel (PDSCH) from a non-terrestrial network (NTN) in a wireless communication system, the UE comprising: a radio frequency (RF) transceiver; and a processor connected to the RF transceiver, wherein the processor receives semi-persistent scheduling (SPS) configuration information, receives first downlink control information (DCI) that activates an SPS configuration related to the SPS configuration information, and receives the PDSCH based on the SPS configuration, by controlling the RF transceiver, wherein the SPS configuration is activated based on a value of a hybrid automatic repeat and request (HARQ) process number field and a value of a redundancy version (RV) field included in the DCI, wherein the SRS configuration information includes information on first indexes for a first SRS configuration in which the HARQ process is enabled and second indexes for a second SRS configuration in which the HARQ process is disabled. 13-15. (canceled) 